Vans removed victims from the mortuary after identification
DNA tests will be needed to identify many of the 153 people killed in Wednesday's plane disaster at Madrid airport, the Spanish government says.
Deputy Prime Minister Maria Teresa Fernandez de la Vega said experts had so far only been able to identify 59 people using fingerprint analysis.
The air disaster, in which a departing jet caught fire after veering off the runway, was Spain's worst in 25 years.
Vigils were held on Thursday to remember those who died.
Spanish media reports suggest an as-yet unreleased video taken by Spain's Civil Aviation Authority (AENA) shows the plane taking off and then crashing moments later just past the runway at Madrid's Barajas airport.
AENA officials quoted in El Pais newspaper suggest the jet may have suffered a chain of faults, and only caught fire after it hit the ground, contradicting witness accounts that an engine was ablaze during take off.
It will be weeks, maybe months, before the truth is known about what caused the plane to crash, the BBC's Johnny Dymond reports from Madrid.
There has been much criticism of the flight operator, Spanair, but there is little to back it up at present, our correspondent says. Until the contents of the flight recorders are analysed, the final minutes of the flight will remain a mystery, he adds.
The remains of the dead have all been taken to a mortuary at Madrid's Ifema congress centre, which was used to collect victims of the Madrid train bombings of 2004.
I lifted my head and all I saw were scattered bodies
"All of them have undergone autopsies," said Ms Fernandez de la Vega. "The investigation commission is working very intensively, and hand-in-hand with foreign experts."
Of the survivors of the Spanair flight JK 5022 crash on Wednesday, several remain critically ill. Four are in a "very serious" condition, with another listed as "serious", Spanish media reported.
But five of six people classed as "serious" showed signs of improvement on Thursday, according to Spanish news agency Efe. Eight of the injured remain under observation with one only slightly injured, Spanish media said.
Harrowing reports of the crash have been emerging from among the survivors.
"The plane was rocking from one side to another," said Ligia Palomino, who survived with leg injuries and cuts to her face.
"I don't know what happened next. I saw people, smoke, explosions - I think that is what woke me up because I had lost consciousness.
"I lifted my head and all I saw were scattered bodies," added the 41-year-old doctor. "I thought that if help did not arrive soon I would die."
Footage of the immediate aftermath of the crash site
Two babies and 20 children were on board the flight, which was heading from Madrid to Las Palmas in the Canary Islands, according to Spanair, which released the official passenger manifest. Three children survived the crash.
Nineteen foreigners from at least 11 countries were on the plane, the Spanish government said. The countries include Germany, France, Sweden, Mauritania, Turkey, Brazil, Indonesia, Bulgaria, Italy, Colombia and Gambia.
Spanish leaders met relatives of the victims on Thursday as the country observed national mourning.
The Spanair flight, bound for Las Palmas in the Canary Islands, took off on Wednesday at lunchtime with 172 people on board, including 10 crew members.
Initial reports suggested a fire had broken out in one of the MD82 plane's engines during take-off, and the plane ended up in a field.
Spanish Transport Minister Magdalena Alvarez said the plane had earlier begun taxiing to the runway, before turning back because of a technical problem, which had caused an hour's delay in take-off.
The pilots had reported a fault with a temperature gauge, Spanish media reported, but it was thought to have been fixed before take-off.
El Pais newspaper quoted experts as saying that fault was unlikely to be responsible for the crash.
"The fault fixed by Spanair's maintenance technicians could not have had an influence on the crash," Jose Maria Delgado, the head of Spain's Association of Aeronautic Maintenance Technicians told the newspaper.
Manuel Batista, the head of the AENA, told El Pais there was "more than one breakdown".
He added that engine failure alone would not have been enough to bring the plane down.
"I am not so sure that the engine failed," said Mr Batista.
El Mundo newspaper suggested parts of the engine may have broken off and damaged the plane's tail.
A special independent commission has been established to investigate the cause of the crash.
Speaking on Thursday, Ms Alvarez said the investigation would examine flight recorders and available pictures, but added that it was very early to draw conclusions about the crash.
The plane which crashed was a 15-year-old McDonnell Douglas MD82 plane previously owned and operated by Korean Air. Reports said it was serviced regularly and had been pronounced fit to fly.
The MD82 is known as a versatile and reliable aircraft, with some 432 planes currently in service around the world, Efe said.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.