PESHAWAR, Pakistan (AP) An explosion struck the office of an aid organization in northwestern Pakistan near the Afghan border on Saturday, wounding a security guard, police said.

It was the ninth attack in two weeks in and around Peshawar, the largest city in the northwest and the main gateway to the al-Qaida and Taliban-infested frontier region. The area has been increasingly targeted as militants retaliate against an army offensive aimed at routing Taliban militants from a nearby region.

The bomb was set off with a timer at about 7 a.m. near the office's perimeter wall, said Liaquat Ali Khan, the police chief in Peshawar. The building belonging to Shift International, a group helping handicapped people, was damaged, he said.

The blast came a day after two police officers were killed and four others were wounded in a roadside bombing in Peshawar. A suicide bomber also killed 19 people in the city on Thursday.

Pakistan expressed fear Friday that an increase of U.S. troop numbers in Afghanistan could push militants across the border into its territory and called on the Americans to factor in that concern as part of their new war strategy.

The Pakistani concerns, raised by the prime minister during a meeting with visiting CIA director Leon Panetta, could pose another headache for President Barack Obama as he weighs military proposals to send 10,000 to 40,000 additional U.S. troops to Afghanistan next year.

Prime Minister Yousuf Raza Gilani said the United States must fully share its plans for Afghanistan with Pakistan so that it can contribute to them, according to a statement from his office.

The U.S. Embassy declined to comment on the CIA director's visit to the country. American security and government leaders have frequently visited Pakistan in recent weeks to urge it to do more against militants on its side of the border blamed for violence inside Afghanistan.

Pakistani officials have said in the past that they were worried that Obama's original surge of 21,000 troops this summer would lead to more militants crossing over into the country, something that has not happened.

Also, U.S. plans to close remote posts near the border and instead focus on larger population centers in Afghanistan have sparked fears that militants will now find it easier to move between the two countries.

Pakistan's government is under domestic pressure not to be seen simply taking orders from the United States and give the impression it has a say in any new Afghan policy. As such, Gilani's statement could have been as much directed at a local audience as to the Americans.

Pakistan's army launched an offensive against the Taliban in South Waziristan in mid-October an effort welcomed by Washington. It has retaken many towns in the lawless region, but many militants are believed to have fled north to escape the fighting and have retaliated with deadly bombings and clashes.

Four Pakistani soldiers, including a captain, were killed Friday when militants ambushed their convoy in the North Waziristan area of Shawal, local intelligence officials said.

A suspected U.S. missile strike also killed eight militants in a village elsewhere in northwestern Pakistan, intelligence officials said, the second attack this week in an area believed to hold many insurgents who fled from an army offensive elsewhere in the Afghan border region. American officials generally do not acknowledge the unpopular attacks.

The U.S. drone fired two missiles at a compound being used by suspected Taliban militants in a village near Mir Ali in North Waziristan, according to two intelligence officials.

The officials all spoke on condition of anonymity because they weren't authorized to release the information

Another suspected U.S. missile strike killed three militants and wounded four just after midnight Thursday in Shana Khuwara village in North Waziristan, officials said.

Anti-American sentiment is pervasive throughout Pakistan. The Pakistani government publicly condemns the U.S. strikes as violations of its sovereignty, but many analysts believe the two countries have a secret deal allowing them.

Associated Press writer Rasool Dawar in Mir Ali contributed to this report.