An eighth body has been found in the wreckage of an Amtrak train two days after it derailed in Philadelphia.

Fire Commissioner Derrick Sawyer said the remains were discovered on Thursday morning with the help of a sniffer dog.

The victim's identity was not released.

Philadelphia Mayor Michael Nutter told a press conference it was a "near miracle" that most passengers survived.

He said that all 243 people on board the train had now been accounted for from the manifest.

The train was going at 106mph (170kph) before it derailed on a sharp curve where the speed limit is 50mph, say investigators.

At Thursday's news conference, Mayor Nutter stood by his criticism of the driver a day earlier.

"I don't think that any common sense rational person would think that it was ok to travel at that level of speed," he said.

The mayor confirmed that the train driver, Brandon Bostian, refused to give a statement to police.

The 32-year-old Amtrak engineer has concussion and cannot remember the incident, according to his lawyer.

Attorney Robert Goggin told ABC News: "He remembers coming into the curve.

"He remembers attempting to reduce speed and thereafter, he was knocked out."

He said Mr Bostian had surrendered his mobile phone and consented to a blood test.

More than 200 passengers were injured when the Washington-to-New York train derailed on a bend on Tuesday night.

Forty-three people remain in hospital, eight in a critical condition.

The National Transportation Safety Board (NTSB) said federal accident investigators want to talk to Mr Bostian, but will give him a day or two to recover.

The derailment happened along the country's busiest rail corridor, between Washington and Boston.

Amtrak's president has said its Northeast Corridor service will be fully restored by Monday or Tuesday next week.

Tributes have been paid to those killed in the crash, including a young sailor, a software architect and a chief executive.

The NTSB said the engineer applied the emergency brakes moments before the crash.

The train had slowed to only 102mph by the time the locomotive's data recorder stopped.

The speed limit just before the bend is 80mph.

Amtrak had not installed technology that prevents trains from speeding along that section of track.

The publicly funded rail utility has been under pressure from Congress and safety regulators to do so.