The sharp drop in violence that has accompanied the US troop buildup in Iraq has given the war-torn country a rare opportunity for stability, analysts have said.

The panel of independent experts on Iraq told a US House of Representatives subcommittee that the fragile successes of recent months in Iraq could easily unwind if the United States is unwilling to maintain a large troop presence in the Gulf region for years to come.

'We may have an opportunity in Iraq that has not been available since 2003 to stabilise the country and avert the downside risks of failure,' Stephen Biddle of the Council on Foreign relations told the House Armed Services hearing.

They said the current lull in violence could be exploited to hold provincial elections that would help ease friction between elected officials and tribal sheikhs.

They also recommended expanding cease-fire agreements, like the ones that have bought relative calm to previous hotspots such as Anbar province, into northern provinces.

But the analysts said a stable Iraq was less likely to resemble a model democracy than modern-day Bosnia or Kosovo, both volatile countries with substantial international civilian and military presences.

The hearing by the armed services oversight and investigations subcommittee was held to examine US options at a time when the Bush administration is scheduled to withdraw about 20,000 troops from Iraq by mid-summer.

The brigades were the extra forces sent a year ago to quell sectarian violence between Sunnis and Shi'ites. There are currently about 158,000 US troops in Iraq.

Lawmakers were told that the 60 per cent drop in violence last year was due largely to Sunni tribal leaders' backing of the US military against Al Qaeda in Iraq and radical Shi'ite cleric Moqtada al-Sadr's call for loyal Shi'ite militiamen to stand down.

Those developments, combined with an apparent reduction of Iranian support for violent Shi'ite militias, have altered the calculus of sectarian differences in the country and cast the US mission in a more positive light, they said.

'While the US presence may have stoked insurgent violence in Iraq between 2003 and 2006, the U.S. is, for now, a force for stability,' said Michael Eisenstadt of the Washington Institute for Near East Policy.-Reuters