CHICAGO: Nato's chief urged Islamabad to back efforts to stabilise Afghanistan as he prepared for talks Saturday with Pakistani President Asif Ali Zardari, on the eve of a Nato summit.

Zardari was invited to the summit in Chicago amid expectations that Pakistan will lift a six-month blockade against Nato supply trucks that was put in place after US air strikes killed 26 Pakistani troops in November.

Nato has also pressed Islamabad to do more to prevent insurgents from taking advantage of the porous Afghan-Pakistani border region to take sanctuary inside Pakistan.

“We can't solve the problems in Afghanistan without the positive engagement of Pakistan,” Nato Secretary General Anders Fogh Rasmussen said at a policy forum in Chicago, which is hosting the summit on Sunday and Monday.

“We have to solve these problems,” he said, referring to the safe havens used by insurgents in Pakistan to launch attacks on Nato troops across the border.

When he meets with Zardari later, Rasmussen said he would “convey a couple of clear messages,” but he did not elaborate.

US President Barack Obama will host fellow leaders for two days of talks focused on plans to gradually hand over security control to Afghan forces and pave the way for the withdrawal of 130,000 foreign combat troops by late 2014.

Nato hopes Afghanistan's security forces, which will grow to 352,000 later this year, can take the lead throughout the country next year, enabling foreign troops to gradually switch from combat to training mode.

But France's new President Francois Hollande has shaken up the carefully crafted transition plan, vowing to bring his 3,500 combat troops home this year, a year earlier than planned.

“The withdrawal is not negotiable. The withdrawal of combat forces is France's decision and this decision will be implemented,” Hollande told reporters after White House talks with Obama on Friday.

Hollande, however, said he would honor a treaty signed by his predecessor Nicolas Sarkozy to provide training support for Afghan police and military forces.

Highlighting the challenges facing Afghan security forces, a suicide bomber struck at a lunch gathering of police and local civilians in the country's southeast on Saturday killing at least 13 people, three of them policemen.

Despite the early French withdrawal, Nato wants to show a united front in the last two years of combat in an increasingly unpopular war in Europe and America.

The alliance will also use the summit to reassure Afghan President Hamid Karzai that Nato will fund his security forces and continue training beyond 2014.

“Let me be clear,” Rasmussen said. “Nato will continue to stand shoulder to shoulder with Afghanistan.”