The surviving Boston marathon bombing suspect has been transferred from a hospital to a prison medical facility, the US Marshals Service was quoted as saying Friday.

Dzhokhar Tsarnaev, 19, was sent to the Federal Medical Center Devens, near Boston, spokesman Drew Wade told CNN.

The facility is about 40 miles (65 kilometers) northwest of the Boston-area hospital where Tsarnaev had been convalescing since he was found critically wounded in a boat in a massive police manhunt, days after the bombing which killed three and wounded 264.

His elder brother Tamerlan died in a wild shootout with police that same night as they tried to flee Boston in a hijacked car.

The US Marshals Service and the prison medical facility could not immediately be reached to confirm the report.

The reported transfer came a day after officials said the brothers had planned to detonate more explosives in Times Square in New York as they were being hunted by police.

New York police chief Ray Kelly said the pair intended to use a pressure-cooker bomb -- similar to the two that erupted at the marathon -- as well as five pipe bombs and improvised grenades they still had on hand as they drove around in a hijacked black Mercedes.

Dzhokhar Tsarnaev confessed the plan to Federal Bureau of Investigation agents in his hospital bed, Mayor Michael Bloomberg said, calling it a "horrific reminder that we remain targets for terrorists."

"Last night, we were informed by the FBI that the surviving attacker revealed that New York City was next on their list of targets," Bloomberg told reporters Thursday.

The pair -- accused of carrying out the attacks near the Boston Marathon finish line -- aimed to use their remaining explosives in Times Square, he added.

They made a "spontaneous" decision to go to New York as they raced around the Boston suburbs in a car with at least six bombs, according to Kelly.

The night finished with a policeman killed and another gravely wounded, besides one of the suspects dead and the other wounded.

But the Republican chairman of the House Intelligence Committee disputed that claim, saying it was more likely the Tsarnaev brothers were planning another attack in Boston instead.

"It's not clear to me that they were actually going to set those devices off, even though they had them with them," Representative Mike Rogers told CNN.

"It's more plausible to me (that) they were going to do another event in the Boston area, and they were hiding out in New York City, (that) was their plan."

Rogers said that ever since the younger Tsarnaev, who is recovering from a bullet wound to his throat, was read his Miranda rights to consult a lawyer and to remain silent, he "has not continued to cooperate with the authorities."

And there are still other "persons of interest" who have yet to be interrogated in the case, Rogers added.

Kelly revealed on Wednesday that Dzhokhar Tsarnaev had told investigators that the pair planned to go to New York "to party."

However, "a subsequent questioning of Dzhokhar revealed that he and his brother decided spontaneously on Times Square as a target," Kelly said at the joint news conference with Bloomberg.

New York police have bolstered security in Times Square since a foiled 2010 plot to set off a car bomb.

The brothers' plan "fell apart when they realized that the vehicle that they hijacked was low on gas and ordered the driver to stop at a nearby gas station. The driver used the opportunity to escape and call the police," Kelly said.

The call unleashed a manhunt involving thousands of police.

Dzhokhar Tsarnaev has been charged with using a weapon of mass destruction and could face the death penalty if convicted in US federal court.

There have been mounting questions in the United States about whether the US authorities missed crucial signals, about Tamerlan in particular, that should have raised suspicions about the brothers before the bombings.