UNITED NATIONS - The U.N. Security Council might take up this month the issue of Iran's nuclear program and Western proposals for a fourth round of sanctions against Tehran, Gabon's U.N. envoy said on Tuesday.

Ambassador Emanuel Issoze-Ngondet, who is president of the Security Council for the month of March, said the Iranian nuclear issue was not on the agenda of the 15-nation panel this month, but council members might still hold a meeting on it.

We think the question could come to the table (in March), Issoze-Ngondet told reporters through an interpreter. But right now we are waiting. We're following the process that's ongoing. We're waiting for the right time to bring the Security Council to deal with it.

Speaking on condition of anonymity, Western diplomats told Reuters the United States, Britain, France and Germany have prepared a draft proposal -- which they hope China and Russia will support -- for a fourth round of sanctions against Iran for refusing to halt its uranium enrichment program.

The four Western powers had hoped to secure an agreement among the six as early as this week, so they could submit it to the full Security Council for discussion. But it has been difficult getting China to negotiate, the diplomats said.

We still don't know what China thinks, a diplomat told Reuters.

China and Russia have close business ties to Tehran, but Moscow has indicated its willingness to support further punitive measures against the Islamic Republic, which rejects Western allegations that its nuclear program is a cover for developing the capability to build atomic weapons.

Originally U.S., British, French and German officials had hoped the 15-nation Security Council could vote on a new Iran sanctions resolution by the end of March, but some diplomats say they worry negotiations will run into April.

As permanent council members, China and Russia hold veto power, as do the United States, Britain and France.

QUESTIONS ABOUT CHINA

The Western powers' proposed sanctions would target Iran's Islamic Revolutionary Guard Corps and expand the number of individuals, banks and other firms subject to asset freezes and travel bans, diplomats said.

Among the firms to be targeted is Iran's central bank.

France has been urging its Western allies to hit Iran's oil and gas industries. Washington, diplomats say, has proposed less stringent measures, such as a ban on new investments in Iran's energy sector.

However, Russian Foreign Minister Sergei Lavrov made clear on Tuesday that Moscow had not abandoned diplomatic efforts without resorting to sanctions to persuade Tehran to comply with U.N. demands to freeze sensitive nuclear activities.

Western diplomats say they hope to secure a yes vote from Beijing for a sanctions package, though it might have to be more symbolic than painful for Tehran.

But they also said it was possible that China would only agree to abstain, which would avoid a Chinese veto but would send the message to Tehran that Beijing is not on board.

Security Council diplomats say that non-permament council members Brazil, Turkey and Lebanon were expected to either abstain or vote against steps that would punish Tehran.
The first two Iran sanctions resolutions were adopted unanimously in 2006 and 2007. The third was approved in March 2008 with 14 votes in favor and an abstention by non-permanent council member Indonesia.

(Editing by Doina Chiacu)