BUENOS AIRES - An Argentine federal judge Thursday ordered a committee of experts be formed to investigate the deadly commuter train crash that killed at least 50 people and injured 703 others Wednesday morning.

Federal Judge Claudio Bonadio, who is in charge of the inquiry, said he had asked two engineers with the University of Buenos Aires and an expert from the Supreme Court to form a committee and conduct a thorough investigation into the cause of the accident.

Bonadio also asked transport departments to assist in the probe.

Buenos Aires' residents search lists posted on the wall of the names of more than 700 commuters injured in a train crash on Wednesday at Once train station in Buenos Aires Feb 23, 2012.[Photo/Agencies]

The accident has killed 50 and injured 703 others so far, the latest official figures showed.

All the victims have been identified and most of the wounded have left the hospital, while 46 with grave injuries are still being treated, Minister of Federal Planning, Public Investment and Services Julio de Vido said.

The Argentine government will participate in the inquiry and take part in the trial as a plaintiff. Once the judicial authorities determine the cause of the accident and the people accountable, the government will take "decisive measures" to protect the public's interests, the minister said.

Transport Secretary Juan Pablo Schiavi said the train entered the station at a speed of 20 kph and slammed into a retaining wall at the end of the tracks. Dysfunctional brakes were suspected to have caused the crash.

Marcos Antonio Cordoba, the train's veteran 28-year-old motorman, is being treated in a private clinic under police protection, officials said. Alcohol tests showed he had not been drinking before driving. No charges have been filed against him.

Argentine President Cristina Fernandez has declared a two-day national mourning, starting Thursday, for victims of the country's worst railway accident in three decades.