U.S. President Barack Obama called his Pakistani counterpart, Asif Ali Zardari, Wednesday to discuss strained bilateral relations and the situation in the region.

A Pakistani statement says the two leaders agreed to take appropriate action to repair the ties between Washington and Islamabad on the basis of mutual respect and mutual benefit.

It says President Obama appreciated Pakistan's effort in the fight against militancy.

President Zardari said the fight against extremism was in Pakistan's own interest and that it had to fight it to the finish.

The two presidents also agreed on “regular contacts and interaction at appropriate levels for the resolution of issues.”

Ties between the two countries worsened significantly after the May 2 raid by U.S. special forces that killed Osama bin Laden in the northern Pakistani city of Abbottabad. The military operation has embarrassed Islamabad, which was not informed beforehand of the raid.

Also Wednesday, Pakistan's army said it was questioning four more officers about suspected ties to the banned Islamic extremist group, Hizb-ut-Tahrir.

An army spokesman said the four army majors are being questioned for suspected links with the group, but have not been detained.

The interrogation of the officers comes a day after the army said it detained Brigadier General Ali Khan over his links to the group.

Hizb-ut-Tahrir is an international Islamist organization that calls for a return to a pan-Islamic Caliphate under Islamic law. Although the group does not advocate violence, it is believed to have links to militant groups.

Many critics in Pakistan and around the world say the Pakistani military is deeply infiltrated by extremist groups, making suspect its loyalty in the international effort against terrorism.

The discovery of Osama bin Laden in Pakistan has raised questions as to whether members of Pakistan's military or intelligence knew the al-Qaida leader was hiding out not far from the capital.