KABUL (REUTERS) - The release of five Taleban prisoners in exchange for a United States soldier has drawn criticism from some Afghans, who say the detainees are dangerous and will rekindle ties with terrorist networks to resume fighting, just as most foreign troops leave.

The men had been held at the US naval base at Guantanamo Bay, Cuba since 2002 and were classed by the Pentagon as"high-risk" and "likely to pose a threat". Two are also implicated in the murder of thousands of minority Shi'ite Muslims in Afghanistan, according to the US military.

They were released in a swap with US army sergeant Bowe Bergdahl, the sole American prisoner of war held in Afghanistan who was flown to a US military hospital in Germany on Sunday.

"They will definitely go back to fight, if health-wise they are able to go," said a top official at Afghanistan's spy agency, who asked to remain anonymous because of the sensitivity of the topic. "They will be very dangerous people, because they have connections with regional and international terror organisations around the world."

The Taleban denied the prisoners would return to battle but said the swop should not be regarded as a gesture of goodwill or a step towards the revival of peace talks between Islamist insurgents and the Afghan government. "This is purely a negotiation between the Taleban and the Americans... It won't help the peace process in any way, because we don't believe in the peace process," said Taleban spokesman Zabihullah Mujahid.

The prisoners would return to their families and live in Qatar - the Gulf emirate that brokered the exchange - where they would lead normal lives, he added.

US Defence Secretary Chuck Hagel expressed hope on Sunday that the release of Sgt Bergdahl would lead to direct US talks with the Taleban.

In an interview with NBC's Meet The Press programme, Mr Hagel noted that the United States had engaged in talks with the Taleban before, until they were broken off in 2012. "So maybe this will be a new opening that can produce an agreement," he said.

The prisoner swop comes just days after the United States announced plans to withdraw all but 9,800 troops from Afghanistan by the end of the year and the rest by 2016.

Many senior Afghan officials and diplomats say the drawdown will happen much faster than expected and reflects a US desire to disengage from Afghanistan as quickly as possible.

The prisoner swop is further evidence of US efforts to tie up as many loose ends as possible before leaving, diplomats say. "They have made a mess of things," said one Western diplomat, frustrated with the pace of the drawdown.

In a further reflection of the rupture in relations between the two countries, the United States did not inform President Hamid Karzai's government about the swop in advance.

His palace declined to comment.

On the streets of the capital Kabul many expressed anger at the decision to release the five men, a contrast with scenes of celebration in Sgt Bergdahl's home town in Idaho.

"This decision showed that the region, Afghanistan and its people aren't worth anything to American government," said Mr Gul Mohammad, a high-school teacher. "Otherwise, why would they swop a useless army soldier who broke the law with the five most dangerous Taleban fighters?"

Some among Afghanistan's security forces also expressed unease about the release, which comes as the Taleban's summer offensive gathers pace ahead of a second round of voting in the presidential election on June 14. "This act will boost the Taleban's morale and encourage them to fight harder to capture foreign soldiers. Now they are confident that their efforts won't be wasted," said army colonel Asadullah Samadi.