U.S. policymakers must keep pressure on President Pervez Musharraf to hold fair elections in Pakistan next month or risk deeper chaos in the nuclear-armed country, an important ally in Washington's anti-terror campaign, experts told Congress on Wednesday.

A House of Representatives panel heard from leading South Asia experts that prospects for free and fair elections in Pakistan on February 18 were doubtful under restrictions imposed late last year by Musharraf.

"Maximally free and fair elections are required for near-term stability," RAND Corporation analyst Christine Fair told the House Subcommittee on the Middle East and South Asia.

"In the short term, the United States should work toward a democratic transition in Pakistan, not merely a democratic patina for President and General Musharraf," she said.

The United States should avoid abrupt moves such as abandoning Musharraf, or cutting off aid to military. But it must not allow him to engineer a fraudulent poll that would anger many Pakistanis, the experts said.

Musharraf, who took power in a military coup in 1999 but was embraced by Washington after the September 11 attacks, imposed emergency rule in November. Limits on civil rights remain in effect despite a formal end to the crackdown last month.

The United States should use pressure and incentives to prod Musharraf to reinstate the top judges he removed, create an election commission, modernizer voter lists and lift restrictions on political parties and the media, Fair said.

"Musharraf is very unlikely to take these steps, especially without a clarion statement, in public and in private, from the administration and from Congress that such measures are expected," she said.

Musharraf needs an election outcome that would prevent legal or political challenges to his staying in office as president, Ashley Tellis of the Carnegie Endowment for International Peace told the panel.

The Pakistani president is expected to try before the election to ensure a victory for his allies in the Muslim League-Q party or to engineer a favourable outcome after the votes are tallied, he said.

A free and fair election that meets international standards was unlikely. But to avoid more unrest, the goal should be a vote that is "acceptable in terms of process and outcome to the Pakistani people."

To achieve this, the United states and others should "work with Musharraf and prevent the fixing of the election in an egregious way," said Tellis.