The US is investigating whether Al Qaeda was involved in a Christmas Day attempt to blow up a passenger jet, but there is no early evidence the Nigerian suspect in the case was part of a larger plot, said the US homeland security chief.

The 23-year-old suspect, Umar Farouk Abdulmutallab, was moved to prison from a hospital and a court hearing is due for Monday in Detroit, where prosecutors plan to seek an order to obtain his DNA.

He is charged with attempting to blow up a Northwest Airlines jumbo plane as it approached Detroit on a flight from Amsterdam with almost 300 people on board.

Asked whether al Qaeda was involved, Homeland Security Secretary Janet Napolitano told ABC's 'This Week' program, 'That is now the subject of investigation, and it would be inappropriate for me to say and inappropriate to speculate.'

'Right now, we have no indication that it is part of anything larger,' Napolitano told CNN's 'State of the Union.'

But a US law enforcement official, speaking on condition of anonymity, confirmed media reports that Abdulmutallab had told investigators al Qaeda operatives in Yemen had given him the device and told him how to detonate it.

In a separate incident on Sunday, the crew of that same Amsterdam to Detroit flight reported an emergency because of an unruly passenger. The plane landed safely and a Nigerian man was taken into FBI custody.

The man raised concerns after spending a long time in the plane's bathroom, but it turned out he had a 'legitimate illness,' the Department of Homeland Security said.

President Barack Obama, on vacation in Hawaii, stressed the importance of maintaining heightened security for air travel, the White House said after Sunday's short-lived scare.

On Friday's flight, Abdulmutallab was overpowered by passengers and crew after setting alight an explosive device attached to his body, and was treated for burns at a Michigan hospital. He was released from the hospital Sunday morning and moved to an undisclosed location.

'He is in federal custody. He is in a prison,' said Kevin Pettit of the U.S. Marshal's office in Detroit.

Security worries

Republicans appearing on Sunday television programs questioned whether the Obama administration was doing enough to monitor security threats, noting that Abdulmutallab's father had reported concerns about his son to the US Embassy in Nigeria.

'There's much to investigate here. It's amazing to me that an individual like this who was sending out so many signals could end up getting on a plane going to the U.S.,' Senate Republican Leader Mitch McConnell said on ABC.

Obama appealed through his spokesman Robert Gibbs for Republicans and Democrats to avoid a political fight.

'I hope that everyone will resolve in the new year, to make protecting our nation a nonpartisan issue rather than what normally happens in Washington,' Gibbs said on NBC.

Security officials were investigating how Abdulmutallab had been able to get explosive materials onto the plane despite higher security worldwide since the September 11, 2001, hijacked airline attacks in the United States. Al Qaeda was held responsible for those attacks.

Napolitano said authorities were reviewing rules on who goes on lists to identify people who might pose threats and also would review screening policies and technologies.

The U.S. government created a record of Abdulmutallab last month in its central repository of information on known and suspected international terrorists, U.S. officials said. That list has some 550,000 people on it.

Gibbs told CBS' 'Face the Nation' the father's information led to Abdulmutallab's entry into that database. But he added, 'There was not enough information to bring him more forward to either the selectee or the no-fly database list.'

Napolitano and Gibbs sought to reassure travelers that they would be safe.

'Everybody played an important role here. The passengers and crew of the flight took appropriate action,' Napolitano said of the Northwest Airlines flight 253, a Delta-owned Airbus 330.

'The whole process of making sure that we respond properly, correctly and effectively went very smoothly,' she said.

Peter King, the top Republican on the House of Representatives Homeland Security Committee, disagreed.

'He made it on the plane with explosives and he detonated explosives. If that had been successful, the plane would have come down and would have had a Christmas Day massacre with almost 300 people murdered. So this came within probably seconds or inches of working,' King said on CBS.

Airports and airlines in the United States and around the world have tightened security after the foiled attack.

An initial FBI analysis found the device used by Abdulmutallab contained PETN, also known as pentaerythritol, one of the explosives carried by 'shoe bomber' Richard Reid in his failed attempt to blow up a US passenger jet just before Christmas in 2001, months after the September 11 attacks.

The device consisted of a six-inch packet of powder and a syringe containing a liquid, which were sewn into the suspect's underwear, according to media reports.

A Dutch passenger, Jasper Schuringa, was credited with subduing Abdulmutallab as he was igniting the explosives.

In an interview with CNN, Schuringa said he saw Abdulmutallab was holding a burning object between his legs. 'I pulled the object from him and tried to extinguish the fire with my hands and threw it away,' Schuringa said.

Abdulmutallab started his journey in Nigeria's commercial hub of Lagos, where he boarded a KLM flight to Amsterdam before going through another security checkpoint at Schiphol airport, Dutch counter-terrorism agency NCTb has said.-Reuters