Officials confronting the “unprecedented mystery” of missing Malaysia Airlines flight MH370 are to extend the area of their search after a day filled with reports of possible sightings of debris from the aircraft ended with nothing but more frustration.

This is even as investigators hunt for two suspects described by Azharuddin Abdul Rahman, the head of Malaysia’s Civil Aviation Authority, as “looking like Mario Balotelli”.

Mr. Rahman said both an oil slick and a yellow object initially thought to be to a life raft, had proved to have no link to the aircraft.

“Unfortunately we have not found anything that appears to be objects from the aircraft, let alone the aircraft,” he said. “As far as we are concerned, we have to find the aircraft. We have to find a piece of the aircraft if possible.”

In a statement, Malaysia Airlines said the western coast of the country, near the Straits of Malacca, was “now the focus” of the hunt. That is on the other side of peninsular Malaysia from where flight 370 was reported missing, meaning if the plane went down there it would have had to fly over the country. Malaysia’s air force chief said Sunday there were indications on military radar that the jet may have done a U-turn.

Mr. Rahman said the Malaysia Airlines statement didn’t imply authorities believed the plane was now more likely to be off the western coast. “The search is on both sides,” he said.

He did confirm that investigators pouring over CCTV footage of two passengers who boarded the flight using stolen European passports had concluded they were “not Asian looking men”. Earlier another official had said one of the men was not Malaysian.

When asked to give a rough description of the passengers, he referred to Mario Balotelli, the black Italian footballer who previously played for Manchester City and who is currently a member of the Milan team. When the name was put to Mr. Rahman, he replied: “Balotelli, yes”.

On Sunday, officials appeared to be focusing their attention on up to four passengers who had boarded the Beijing bound flight, including the passengers using stolen Austrian and Italian passports. Mr. Rahman said an examination of the CCTV showed the two men had fully complied with security protocols and that their hand baggage had been checked.

He said investigations were continuing, with the help of the intelligence agencies of other countries. “There is the possibility of a stolen passport syndicate,” he said.

It appears the tickets for the passengers who travelled on stolen passports were purchased from a travel agent in Pattaya, apparently by an Iranian middleman.

Mr. Rahman said the search area would be extended by a 100km radius. Planes and ships from 10 countries are currently scouring the seas around Malaysia and south of Vietnam for a trace of the Boeing 777 which went missing with 227 passengers and 12 crew.

On Sunday evening, it was reported that an oil slick had been spotted 90 miles south of Vietnam’s Tho Chu Island in the Gulf of Thailand. Yet chemical analysis determined it was oil usually used by cargo vessels and not aircraft oil.

At the same time, officials revealed that a yellow object believed to have been a life raft had been inspected and that it had also been ruled out. Apparently it was an empty cable reel, covered in moss.

More than two days after the plane went missing, the final minutes before its disappearance remain a mystery. The plane lost contact with ground controllers somewhere between Malaysia and Vietnam.

Malaysian military officials said on Sunday that the plane, a Boeing 777-200ER, may have turned back from its scheduled route shortly before vanishing from radar screens.

Mr. Rahman said officials had set no time-frame for the search and referred to the search for Air France flight 447 which went missing in 2009 on route from Rio de Janeiro to Paris, killing all 228 aboard.

It took investigators two years to locate the black box recorders and three years to piece together what happened. A report eventually blamed a combination of technical failure and pilot error.

“The experts have said this is a very big area for us to cover,” Mr. Rahman said of the area currently being searched. “We all have to work together to find this aircraft... It will take as long as it takes to find the aircraft.”

With so little progress being made and with nothing to tell the relatives of the passengers who boarded the plane, Malaysia has been criticised for the pace at which it has been working.

A total of 153 passengers on the plane were Chinese and in what may have been at attempt to play the blame game, China on Monday accused Malaysia of failing to provide sufficient information. With tearful relatives holed up in hotel rooms waiting for information, China said Malaysia needed to act more swiftly.

“The Chinese government urges the Malaysian side to step up their efforts to speed up the investigation and provide accurate information to China in a timely fashion,” said Chinese foreign ministry spokesman Qin Gang. “They should also properly manage work related to family members of passengers and follow-up issues.”

Over the weekend, Interpol revealed that stolen passports used by two of the passengers on the plane – one belonging to Austrian Christian Kozel and the other to Luigi Maraldi of Italy - were entered into its database after they were stolen in Thailand in 2012 and 2013.

Financial Times reported that the tickets used by the two passengers using those stolen passports had been bought by an Iranian man in the Thai resort of Pattaya.

A travel agent said an Iranian business contact she knew only as “Mr. Ali” had asked her to book tickets for the two men on 1 March. She had initially booked them on other airlines but those reservations expired and on March 6, Mr. Ali had asked her to book them again.

On Monday evening, the proprietors of the Grand Horizon travel agency were reportedly being questioned by Thai police and Interpol officials.

The Boeing 777 has one of the best safety records of any commercial aircraft in service. Its only previous fatal crash came on July 6 last year when Asiana Airlines Flight 214 struck a seawall on landing in San Francisco, killing three people.

The fact that no distress signal was sent out has let aviation experts to suggest the plane was downed by either some sort of wholesale failure or else an explosion.

Mr. Rahman said that as investigations into the passengers continued, the main focus for the authorities was simply to locate the plane. “As far as we are concerned, we have to find the aircraft. We have to find a piece of the aircraft if possible.”

•Adapted from The Indepenent (London). Photo shows Mario Balotelli.