Syria backs the militant Hezbollah on some issues
Syria, one of five countries to win a two-year seat, immediately hailed its election as granting it a clean bill of health against long-standing allegations that it sponsors terrorism by supporting militant anti-Israel groups.
About 160 of the 177 members of the UN General Assembly voted to elect Syria to the Security Council, a body responsible for maintaining international peace.
Washington, which has launched a war on terrorists and those who harbour them, vowed it would not be cowed by the ballot and that it would continue to pressurise Syria.
'Sheer absurdity'
The US has long accused Syria of sponsoring terrorism through its support in particular for Lebanon's Hezbollah, and its name features on a US blacklist.
Syria had run uncontested in the election for the seat allocated to its 50-nation regional group.
Despite appeals from members of the US Congress and Israel, Washington did not publicly campaign against its candidacy.
Correspondents at the UN say the US would have been unlikely to prevent the election of Syria had it done so, and risked losing face and possibly allies at a time when it is trying to muster the world's approval for its battle against terrorism.
Israel made clear its objections.
"Syria indeed backs terrorist groups inside Syria and outside Syria," said Israel's UN ambassador Yehuda Lancry. "It fails even at the regional level to display any contribution to peace and security."
"It is really a sheer absurdity and a sheer nonsense to have Syria as a member of the Security Council."
Vindicated
But Syria interpreted its election as a measure of international support against such allegations, thanking those countries which supported its nomination.
"This success, with an overwhelming majority, shows beyond any doubt that the international community rejects Israel's allegations and terrorism charges levelled against Syria," read an official statement carried by state television.
"The wide support for Syria constitutes a referendum and a clear message that these allegations are void and false," it added.
The country will replace Tunisia in January, and will bejoined by four other new members - Cameroon, Guinea, Bulgaria and Mexico.
Syria last served on the body 20 years ago.
"I'm proud for this great success," said the Syrian Ambassador to the UN, Mikhail Wehbe.
"Syria will pray to preserve the peace and security in the world."