Zaffar Abbas BBC correspondent in Islamabad

Commonwealth Secretary General Don McKinnon has criticised the Pakistan president's decision to hold a referendum to extend his stay in power.

And several opposition groups in Pakistan have described General Pervez Musharraf's announcement as unconstitutional and have called for a boycott.

The Jamaat-e-Islami party has asked the Supreme Court to prevent the referendum taking place.

In his televised speech on Friday, General Musharraf said the referendum, to be held in the first week of May, is to seek a public mandate to remain president for another few years.

Such a device has also been used in the past by a former military leader in Pakistan [General Zia ul-Haq] to extend his term in office

Don McKinnon

In a statement issued in London, Don McKinnon said the road map given by General Musharraf for the restoration of democracy did not include the holding of such a referendum.

The Commonwealth suspended Pakistan following General Musharraf's 1999 coup.

The Commonwealth secretary general is the first prominent world leader to criticise the move.

Many others are still holding back their comments.

Valued ally after 11 September

Senior Pakistani officials say they are not expecting any international outrage, as General Musharraf is now regarded as an ally of the West because of the support he has given for the US-led military campaign in Afghanistan.

But there has been a strong reaction within the country, where several opposition groups have issued a statement to condemn the move.

Criticism has come from most of the Islamic groups.

The hardline Jamaat-e-Islami party has filed a constitutional petition against the referendum, and has also asked the Supreme Court to investigate remarks made by Mr Musharraf in a speech on Friday.

He is accused of failing to clarify that the referendum would be in violation of the constitution.

Other critics include the mainstream opposition parties of the two former prime ministers, Benazir Bhutto and Nawaz Sharif.

Musharraf has his domestic opponents

Miss Bhutto's Pakistan People's Party says the decision is illegal, unconstitutional and immoral, and the alliance of the six hardline Islamic parties says it plans to start a nationwide campaign for the boycott of the referendum.

One of the serious concerns of the main opposition groups is General Musharraf's declared intention to create a national security council in order to constitutionalise the role of the military in the affairs of governance.

So far, only some of the relatively small political groups have supported General Musharraf's decision.

But the military ruler is convinced that the majority of the people support his policies and that they will come out in big numbers on the day of the referendum to vote in his favour.