BERLIN, April 1: Pakistan called on the United States on Thursday to reinforce troops in neighbouring Afghanistan to defeat Al Qaeda militants and warlords who are thriving on a resurgent opium trade.

Foreign Minister Khursheed Mehmood Kasuri, speaking after Islamabad signed up to an initiative with Afghanistan's other neighbours to combat drugs trafficking, said 19,000 foreign troops was "just not enough" to return the country to stability.

"Warlords have to be knocked out and they can only be dealt with if you take on the drugs trade," he told Reuters in an interview during an Afghan donors' meeting in Berlin.

"This is a major challenge, not just to the Afghan government, which is of course trying to do its best, but also to the United States and the ISAF forces in Afghanistan."

A US-led force of 13,500 soldiers, known as Operation Enduring Freedom, is hunting down Taliban militia and Al Qaeda guerrillas mostly in the south and east of the country along the mountainous border with Pakistan.

NATO commands the 6,500-strong International Security Assistance Force (ISAF), a peacekeeping operation based in Kabul and the relatively stable northern town of Kunduz.

Kasuri said Pakistan, by contrast, had stationed 70,000 soldiers on its western border where leaders of the Al Qaeda network, including possibly Osama bin Laden, are believed to be hiding.

"I understand the problems the United States and European countries have. The problem is there is not much stomach for sending soldiers to Afghanistan," he said. "But unless one is prepared to face this challenge, it won't really go away."

He said Pakistan's recent offensive with 5,000 troops against suspected Al Qaeda militants in the border region of south Waziristan showed the scale of the operations needed.

Afghanistan has re-emerged as the world's leading opium producer, accounting for three quarters of global production, since poppy cultivation was almost eradicated by a ruthless campaign under the Taliban.

Kabul has stepped up its own campaign against the drugs trade, helped by an international effort coordinated by Britain. But the United States has been reluctant to extend the focus of its military drive against Al Qaeda in Afghanistan to include narcotics.

"The US military does not want to admit that the Taliban and Al Qaeda are being fuelled by the drug trade," said Barnett Rubin, an Afghanistan specialist at the Centre on International Cooperation at New York University.

International Security Assistance Force 's current mandate does not permit soldiers to act against opium cultivators and drugs traffickers and there has been a debate over whether it should be extended.

But Kasuri said the main problem remained the small number of international troops in Afghanistan. "I think it's an argument for increasing the numbers first of all, the extension of mandate comes much later," he said. -Reuters