Malaysian police released pictures of the young Iranian man. Photo: BBC
A man travelling on a stolen passport on a missing Malaysian jet was a young Iranian who is not believed to have terrorist links, Malaysian police say.
They say the 19-year-old - named Pouria Nour Mohammad Mehrdad - was probably migrating to Germany.
Investigations are continuing into a second man using stolen documents.
The Beijing-bound Malaysia Airlines Flight MH370 vanished on Saturday shortly after it left Kuala Lumpur.
There were 239 people on board.
Experts have said the presence of two people with stolen passports on a plane was a breach of security, but is relatively common in a region regarded as a hub for illegal migration.
Malaysia's police chief Inspector Gen Khalid Abu Bakar said the young Iranian was "not likely to be a member of a terrorist group", adding that the authorities were in contact with his mother in Germany, who had been expecting her son to arrive in Frankfurt.
Without a trace
The authorities' statement supports an account given to the BBC by a young Iranian in Kuala Lumpur who says he was a school-friend of one of the men who boarded the airliner using a stolen passport.
He says the friend and another Iranian, also using a stolen passport, stayed with him before taking the Malaysia Airlines flight, and that they had hoped to settle in Europe.
Reports from Thailand suggest that the tickets of the two men, routing them to Amsterdam via Beijing, had been bought through a Thai travel agent and an Iranian middleman.
Officials say they still have no idea what went wrong.
None of the debris and oil slicks spotted in the water so far have proven to be linked to the disappearance.
Four areas of investigation for the disappearance of the aircraft were focused on the possibility of human agency, the police chief said: hijacking, sabotage, psychological problems or personal problems with passengers or crew.
The passengers on the flight were of 14 different nationalities. Two-thirds were from China, while others were from elsewhere in Asia, North America and Europe.
Meanwhile search teams have expanded their scope to the Straits of Malacca. Malaysian civil aviation chief Azharuddin Abdul Rahman said that the search was ongoing "on both sides" of the peninsula.
Authorities said late on Monday that they were expanding the search area from 50 nautical miles from where the plane had disappeared - over waters between Malaysia and Vietnam - to 100 nautical miles (115 miles; 185km).