ISLAMABAD: Pakistan on Friday submitted to parliament a sweeping package of landmark constitutional reforms, stripping President Asif Ali Zardari of key powers in a move to bolster parliamentary democracy.

The 18th amendment, which rolls back four decades of infringements by military rulers on Pakistan's 1973 parliamentary constitution, is expected to sail through parliament with the required majority and pass into law.

The move has been hailed as a triumph that could ease political instability in the US ally in the war on Al-Qaeda but also one that could build pressure on the government to re-open graft cases against the unpopular president.

Under the constitutional reforms, Zardari would no longer have the power to dismiss the prime minister, dissolve parliament -- as enacted multiple times in the past -- or appoint the head of Pakistan's powerful armed forces.

The 18th amendment would put no bar on prime ministers standing for more than two terms in office -- allowing Pakistan's popular opposition leader Nawaz Sharif, who was toppled by Musharraf in 1999, to again become premier.

Zardari, who is scheduled to address a joint session of parliament next Monday, issued a statement congratulating rival political parties for stitching together the package and called on parliament to adopt the bill "soon".

A euphoric Prime Minister Yousuf Raza Gilani told the lower house that the package was "unprecedented in the history of Pakistan".

"It is historic. Some people think that the prime minister will be stronger now. But in fact these constitutional amendments will strengthen institutions," he said.

The reforms will effectively make Zardari a titular head of state who can only formerly appoint heads of the armed forces, dissolve the national assembly and appoint provincial governors on the advice of the prime minister.

A judicial commission will be responsible for appointing judges and lawmakers on Friday began the process of debating the package.

"This is a bill which will ensure parliamentary supremacy," Raza Rabbani, head of the parliamentary committee on constitutional reform told the lower house of parliament while unveiling the package.

The reforms also devolve greater autonomy to Pakistan's provinces and will rename North West Frontier Province, which dates back to British colonial rule, Khyber-Pakhtunkhwa in a nod to its Pashtun-majority population.

Supporters of the package say that devolving greater power to the provinces, could address some of the grievances of Islamist and separatist insurgents who are destabilising NWFP and southwestern Baluchistan respectively.

"The package is the first significant development in 37 years towards stability of the country and the democratic system," said Jafar Ahmed, political analyst and head of Pakistan Studies at the University of Karachi.

"It is an attempt to ensure the supremacy of the parliament, strengthen democracy and bar dictatorship. The constitution will be more parliamentary, it will strengthen the federation and widen provincial autonomy," he said.

Although Zardari is immune from prosecution while in office, the supreme court is increasing pressure on the government to reopen scores of graft cases at home and abroad, after it scrapped an amnesty shielding politicians.

Tainted by corruption allegations, Zardari is nicknamed "Mr Ten Percent" and spent 11 years in jail on charges ranging from corruption to murder, although his supporters point out that he was never convicted on those charges.

"Since Zardari will be a weak president now, the judicial contest he is facing will be interesting to watch in the days to come," said Ahmed.

Critics say the package stops short of reviewing the colonial-era status of Pakistan's semi-autonomous tribal belt on the Afghan border, which the United States has said is now a global headquarters for Al-Qaeda.

US officials say hundreds of Taliban and Al-Qaeda-linked militants fled into the tribal badlands after the 2001 US-led invasion of Afghanistan and were able to carve out safe havens outside direct government authority.