U.S. Secretary of State John Kerry has held talks in Oman on his latest stop in a campaign to help arrange an internationally-sponsored Syrian peace conference.
A senior State Department official said that while Oman has not played a key role in Syria, it is an "important player" in the region, and Kerry wants to hear Sultan Qaboos bin Said's views.
Oman is a U.S. ally, but also has close relations with nearby Iran.
The issue of Iran's involvement in the proposed Syrian peace conference has divided the United States and Russia, the two nations that first put forth the idea of holding the talks next month.
Russia says Iran should take part. The United States has in the past objected to Iranian involvement, but says no delegations have yet been ruled in or out of the conference. France said last week it does not want Iran there.
European diplomatic sources said Monday that Syrian President Bashar al-Assad has named five officials from his administration to attend the talks, including Prime Minister Wael al-Halki and various junior personnel.
Syria's main opposition group, the Syrian National Coalition, has rejected some of the officials on the list because of their lack of influence. The SNC plans to announce its decision on whether to attend the talks during a meeting Thursday in Turkey.
Kerry's visit is to include talks about Oman's planned $2.1 billion purchase of an air defense system from U.S. defense firm Raytheon.
Kerry will be in Jordan Wednesday for a meeting of the Friends of Syria, where nations backing the opposition will discuss the proposed peace conference.
Meanwhile, Lebanese Hezbollah fighters and Syrian soldiers renewed their offensive Tuesday aimed at driving rebels from the strategic town of Qusair. Opposition activists said Tuesday that more elite Hezbollah fighters have poured across the border from Lebanon into Syria to take part in the assault.
The Britain-based Syrian Observatory for Human Rights said that 31 Hezbollah militiamen have been killed since Sunday in the battle for Qusair.
A senior State Department official briefing reporters in Muscat said the fighting in Qusair is the most visible evidence of Hezbollah joining the fight. He said commanders of the rebel Free Syrian Army report that Iranian forces are also involved in the Qusair battle.
Also Tuesday, the head of Israel's armed forces warned that Syria's president "will have to bear the consequences" if fire continues against Israeli troops across a tense cease-fire line into the occupied Golan Heights.
Lieutenant General Benny Gantz spoke hours after Israeli troops and Syrian forces exchanged fire across the line. The incident marked the first time the Syrian army has acknowledged firing intentionally at Israeli troops since Syria's civil war erupted more than two years ago.