"All options are going to be on the table looking at this," US Assistant Secretary of State for Near Eastern Affairs Jeffrey Feltman told a House of Representatives Foreign Affairs panel.

Israeli President Shimon Peres has publicly accused neighboring Syria of sending Scuds to Hezbollah, a Lebanese Islamist militant group. Syria has denied the charge and said Israel might be using the accusation as a pretext for a military strike.

Feltman declined to say whether the United States had confirmed that any transfers had taken place, saying he was unable to address these concerns in a public hearing.

But he indicated that Washington - which on Monday summoned the senior Syrian diplomat in Washington to address "provocative behavior" regarding the potential transfer of Scuds - was pushing hard to prevent any such shipments.

"If these reports turn out to be true we're going to have to review the full range of tools available to us in order to make Syria reverse an incendiary, provocative action," he said.

"We have to make the case for them not to do it," Feltman said, adding that he had spoken to Syrian Foreign Minister Walid Al-Moualem on the issue on Wednesday and had received a "categorical denial" of any such transfers.

"We're not being passive as we wait and analyze 'will they, will they not do it,'" he said.

The United States has warned that any Syrian effort to re-arm Hezbollah could be a threat to both Lebanon and Israel.

Lebanese Prime Minister Saad Al-Hariri denied on Wednesday that Hezbollah had received long-range Scud missiles from Syria and said the allegations were concocted by Israel to threaten his country.