Joe Biden speaking after meeting Lebanon's president
US Vice-President Joe Biden has voiced strong support for Lebanese democracy and independence during a visit 16 days ahead of key legislative elections.
The tight race could see the militant and political Shia movement Hezbollah gain a parliamentary majority.
Mr Biden said it was up to the voters to choose their own leaders, but the "enduring US partnership" would depend on their commitment to "freedom".
A top Hezbollah official accused the US of "meddling" in Lebanese affairs.
The BBC's Jim Muir in Beirut says, with
in the midst of a bitterly fought election campaign, it was inevitable Joe Biden's arrival would provoke accusations that is trying to help the western allies.
I urge those who think about standing with the spoilers of peace not to miss this opportunity to walk away
"The US will evaluate the shape of its assistance programme based on the policies of the new government," Mr Biden told reporters after talks with
President Michel Suleiman.
Joe Biden was also due to meet the pro-Western Prime Minister Fouad Siniora and Parliament Speaker Nabih Berri, who is allied to the Hezbollah-led bloc.
Correspondents are describing the 7 June vote as a showdown between the US- and Saudi- backed majority from the last parliament and
which is supported by Iran and Syria.
did not mention Hezbollah by name, or its foreign supporters, but correspondents said his statement was a clear warning to voters tempted to vote for the party or its allies.
"I urge those who think about standing with the spoilers of peace not to miss this opportunity to walk away," he said.
The White House said the visit by the vice-president was meant to reinforce US support for "an independent and sovereign Lebanon".
Hezbollah MP Hassan Fadlallah expressed scorn about the visit.
"It appears that this visit is part of a US bid to supervise the electoral campaign of a Lebanese party which feels threatened politically... in light of the expected outcome of the legislative vote," he told AFP news agency.
It is the highest-level US diplomatic visit to Lebanon for many years
The US has given the Lebanese army more than $410m since 2006 - when a devastating war broke out between Hezbollah and Israel - in order to provide a counterweight to Hezbollah's powerful military wing, the Islamic Resistance.
Correspondents say it is unclear to what degree aid would continue under a government led by Hezbollah or its allies.
It included supplying aircraft, tanks and artillery to the Lebanese military and providing training to its personnel.
Washington calls Hezbollah a terrorist organisation, a charge denied by its supporters who say its armed activities are legitimate resistance.
Joe Biden is reported to be the first sitting US vice-president to visit Lebanon.
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