The Afghan intelligence service accused Pakistan on Wednesday of stoking instability in the country by backing militants who stage attacks in Afghanistan.

Spokesman Hasib Sediqi of the National Directorate for Security charged that recent attacks in Afghanistan were planned in Pakistan, allegedly with the support of the Pakistani military's Inter-Services Intelligence agency, or ISI.

Pakistan has denied such accusations in the past.

Sediqi offered no evidence for his claims. He alleged that Pakistan's military campaign against militants in the Waziristan border region had made no progress because the ISI had warned the area's Haqqani militants ahead of launching the campaign. The Haqqani network is an Al Qaeda affiliated Taliban group active in Afghanistan and based in Pakistan's North Waziristan region.

"The main Haqqani leadership has been transferred from North Waziristan two weeks before the operation started, using 150 different kinds of vehicles with their weapons and ammunitions by the direct order of Pakistani intelligence service," Sediqi said, saying that they moved to Pakistan's Kurram Agency -- where there is no ongoing military operation.

Seddiqi said the Pakistani military operation had so far not resulted in the arrest or killing of any major insurgent leader and that the only deaths were from U.S. drone strikes in the same area.

The accusations came as a suicide bomber killed one policeman and wounded three in Afghanistan's northern Kunduz province.

Police spokesman Sarwar Hussaini said the bomber, who was on foot, targeted the Chardara police district chief in Kunduz city.

"Our message to Pakistan is that friendship with Afghanistan will have political and security benefits," Sediqi added.

Violence has been growing in recent months as U.S.-led foreign forces have been steadily withdrawing ahead of a full pull out of all combat forces at the end of the year. A bilateral security agreement between the United States and Afghanistan, and another to follow with NATO, has been delayed until a new president is elected. Election official are now auditing the results of a second round of voting between former finance minister Ashraf Ghani Ahmadzai and former foreign minister Abdullah Abdullah.

If signed, the U.S. and its allies will leave a small force of trainers and advisers.

German Defense Minister Ursula von der Leyen, on her second trip to Afghanistan since she took over the job in 2013, reiterated Germany's stance that it would move ahead with its plans to draw down its forces in the country.

"For us the basic rule still applies: We went into Afghanistan as an alliance and we will leave as an alliance," she said, the dpa news agency reported.

Germany is leaving some 800 soldiers in the country, however, to be part of the planned training mission.

"The most important thing now is together to protect the successes we have achieved," she said.