ISLAMABAD - Pakistan on Thursday summoned the US ambassador to Islamabad to protest the violation of national sovereignty through the operation conducted by US forces in the country's northwestern city of Abbottabad, officials and local media said.

US ambassador Cameron Munter was summoned to the Pakistan's Foreign Office (FO) in capital Islamabad as Pakistan decided to formally protest against the pre-dawn operation that reportedly had killed al-Qaida chief Osama bin Laden on May 2, according to local TV channel DawnNews.

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Foreign Affairs Secretary Salman Bashir told Munter that the US operation was an attack on the country's security and sovereignty.

Bashir termed the Osama's death a success and said Pakistan " will not tolerate" any such operation or violation of its airspace in the future while demanding pre-operation information to Pakistan.

During the conversation, Munter described US wish of improved relations with Pakistan, officials from Pakistani FO said.

Munter, regretting over the violation of Pakistani airspace, said that the said operation was a major and bold step against the world's most wanted person.  

Pakistani government and military have been facing a rising pressure from opposition political parties and public to know about the real role of the institutions. Pakistani Prime Minister Syed Yousuf Raza Gilani, during his address to the parliament, tried to explain his government stance and ordered a probe into the matter.

But one day after his speech, opposition leader and two times former Prime Minister Nawaz Sharif, talking to media, rejected government's stance and demanded a judicial commission to investigate the matter of operation that earned bad name for the nation.