Islamabad, March 24: PML-N chief Nawaz Sharif will boycott the swearing-in ceremony of Pakistan's new prime minister on Tuesday to protest against Pervez Musharraf's presence whom he has called "an illegal and unconstitutional" President.

"His (Sharif's) participation in a presidency-hosted function is out of the question," PML-N spokesman Ahsan Iqbal said on Sunday.

Asif Ali Zardari, Chairman of the Pakistan People's Party that is heading the coalition government, was yet to decide whether he would attend the ceremony, party spokesman Farhatullah Babar said.

The new premier who will head the coalition government being formed by PPP, PML (N) and ANP will be sworn in by Musharraf during the ceremony to be held at 11 AM on Tuesday at the Aiwan-e-Sadr or presidency.

Presidential spokesman Rashid Qureshi said he was unaware if the leaders of the PML-N and PPP were invited to the ceremony.

Senior PML-N leader Chaudhry Nisar Ali Khan said, "We are not boycotting the prime minister's oath-taking ceremony but we believe that President Pervez Musharraf is a stranger in the President's House.

"He is a not a legal and constitutional president and we will not go to the presidency (for the swearing-in)," Khan said.