BEIRUT - U.S. Secretary of State Hillary Rodham Clinton reassured the Lebanese people Sunday that Washington supports "voices of moderation" and will never make a deal with Syria that undermines the country's interests.

Clinton spoke on a surprise visit to Beirut ahead of a critical June 7 election that could see the pro-U.S. Lebanese government ousted by the Iranian-backed Hezbollah and its allies, possibly paving the way for renewed Syrian influence over the country.

"The people of Lebanon must be able to choose their own representatives in open and fair elections without the specter of violence or intimidation and free of outside interference," Clinton told a news conference in Beirut after meeting with President Michel Suleiman.

"Beyond the elections, we will continue to support the voices of moderation in Lebanon and the responsible institutions of the Lebanese state they are working hard to build. Our ongoing support for the Lebanese armed forces remains a pillar of our bilateral cooperation," she added.

Syria dominated Lebanon for nearly three decades before it was forced to withdraw its tens of thousands of troops four years ago this week in the wake of the assassination of former Prime Minister Rafik Hariri. There have been concerns among anti-Syrian factions in the pro-U.S. parliamentary majority that the Obama administration talks with Syria could weaken American support for Lebanon.

But Clinton said she delivered a letter from Obama to Suleiman expressing strong support for a free, sovereign and independent Lebanon. She said U.S. attempts to engage Syria and Iran are not being done at the expense of that support.

"There is nothing that we would do in any way that would undermine Lebanon's sovereignty," Clinton said. "I want to assure any Lebanese citizen that the United States will never make any deal with Syria that sells out Lebanon and the Lebanese people. You have been through too much and it is only right that you are given a chance to make your own decisions," Clinton said.

"It's a complicated neighbourhood you live in and you have the right to your own future," she added.

Hezbollah spokesman Ibrahim Mussawi said Clinton's visit could have a negative impact on the pro-U.S. factions in the country. Speaking on the group's Al-Manar TV after Clinton arrived, Mussawi said it was too early to tell whether the Obama administration has reassessed its policy.

But he added that American "interference in the past was never positive." He also criticized what he termed a "double standard and deception" when the U.S. calls for Islamic factions to participate in elections and then refuses to accept the results if they win.

Clinton, whose first trip to one of the most volatile countries in the Middle East lasted a little less than three hours, would not speculate on the results of the election and what the U.S. would do if Hezbollah wins, stressing a free and fair elections.

"We certainly hope that ... the results of the election will continue a moderate, positive direction that will benefit all of the people of Lebanon," she said at the presidential palace.

But U.S. officials have said they would review aid to Lebanon, including military assistance, depending on the composition of the new government. The United States has provided US$1 billion in aid since 2006, including $410 million in security assistance to the military and the police.

Although the U.S. and Israel regard Hezbollah as a terrorist organization, the militant Shiite group shares power in Lebanon's current government and along with its allies, has veto power on major decisions. A strong showing by Hezbollah would further boost Iranian and Syrian influence in the Mideast and could harm Arab-Israeli peace efforts.

Prior to Clinton's visit, the U.S. ambassador to Lebanon had already expressed concern about the election, and Hezbollah's opponents warned a victory for the militant group could bring international isolation and reduced aid from Washington.

While urging free and fair elections, the Obama administration is treading carefully. The Bush administration encouraged the Palestinian legislative elections in 2006 and then saw the radical Hamas movement win handily and badly damage efforts to broker an Israeli-Palestinian peace deal.

Reflecting that concern, Clinton met during her brief stay with just one senior official, President Suleiman.

U.S. officials say her meeting with Suleiman only is because the U.S. doesn't want to be seen as taking sides in the elections. Suleiman is considered a consensus leader and neutral in the political struggle.

Even if it wins, Hezbollah cannot rule alone because of Lebanon's complex, sectarian power-sharing system in which the major of the 18 sects must be represented in parliament and the Cabinet.

Hezbollah leader Hassan Nasrallah says the group knows that trying to dominate Lebanon's politics would destabilize the country. In the past four years, Lebanon has nearly tumbled into a repeat of the 1975-90 civil war as the pro-Syrian and pro-U.S. camps struggled for the upper hand.

Hezbollah has taken the strategy of a low-key election campaign with a moderate message, aiming to show that a victory by its coalition should not scare anyone.

Nasrallah has even said that if the coalition wins, it would invite its opponents to join in a national unity government to ensure stability.

Before leaving Lebanon, Clinton stopped at Hariri's grave on the main Martyrs' Square in downtown Beirut to lay a wreath and pay respects. She renewed U.S. support for an international tribunal based in the Netherlands to try his killers.

"There needs to be an absolute end to an era of impunity for political assassinations in Lebanon," Clinton said.

Hariri's flower-bedecked grave has been a focal point of political rallies and visits by foreign dignitaries.

Hariri and 22 others were killed in a massive truck bombing on a seaside Beirut street on Feb. 14, 2005. The attack set off massive street protests which, along with an international uproar, forced Syria to withdraw its troops from Lebanon after nearly 30 years of dominating its smaller neighbor.

The tribunal began its work in March. But four years after the assassination, no one has been brought to justice. An early UN probe into the killing concluded the complexity of the assassination plot suggested a role by the Syrian intelligence services and its pro-Syria Lebanese counterpart. Four Lebanese pro-Syrian generals have been under arrest since. But Syria denies any involvement.