LONDON, Feb 05, 2014 (AFP) - The Taleban are living in a "fantasy world" and their chances of achieving their objectives after Western troops leave Afghanistan are extremely low, a military think-tank expert said Wednesday.

The Afghan security forces are "thoroughly in control" of counter-insurgency, said Brigadier Ben Barry, senior fellow on land warfare at the International Institute for Strategic Studies (IISS).

They should be able to successfully protect the April 5 presidential election, though with 11 candidates, it is difficult to predict whether the transfer of power will be smooth, he said.

The Taleban's military offensive in 2013 failed, while their attacks in Kabul had political but negligible security impact, Barry said.

"What we've got now is the Afghan security forces thoroughly in control of doing counter-insurgency and securing Afghanistan," he told AFP at the IISS's London headquarters after the launch of the think tank's main annual report.

He said government forces were holding the military gains made by the NATO troop surge and their ability to retain control would continue to improve. "The most likely security situation after complete transition on January 1, 2015 is a situation very much like today," he said.

The British brigadier, who commanded NATO troops in Bosnia, said the alliance was "very worried" about Afghan President Hamid Karzai's refusal to sign the bilateral security agreement.

The pact would allow about 10,000 US troops to be deployed in the country after NATO withdraws by December. "That, in the long term, is a considerable risk to Afghanistan's security and stability," he said.

He said the Taleban's recent actions showed they were "believing their own propaganda".

"There is evidence from recent Taleban behaviour that they are living in a fantasy world," he said. "It's going to be very difficult to completely eradicate the Taleban, the narcotics trade and corruption," he added.

"But I think the chances of the Taleban achieving their aims militarily next year are very, very low. If Afghanistan after 2015 is able to form a coherent government and able to maintain the capability of the army, the police and their intelligence services, the chances of the Taliban achieving their political objectives remain low."