Syria on Sunday ruled out the UN atomic watchdog making a second inspection of a contested site bombed by Israel last year and alleged by the United States to be the location of a nuclear facility.

The official news agency SANA quoted a foreign ministry source as saying Syria had agreed with the International Atomic Energy Agency (IAEA) that the site should be visited "just one time".

A senior IAEA delegation in late June visited the Al-Kibar site in a remote desert area of northeastern Syria that was attacked by Israel in a secret air raid in September.

"Syria has carried out what it promised in this regard," SANA quoted the source as saying. "If, after visiting the site, the IAEA wants any clarifications then Syria can give answers to them."

Citing intelligence and photographic evidence, the United States says Al-Kibar was a nuclear facility built with North Korean help and close to becoming operational.

But Syria has denied the allegations, saying Al-Kibar was merely a disused military building and insisting the country has no nuclear programme whatsoever.

The foreign ministry source said that the accusations had been made by the United States to justify the "Israeli aggression" against the Al-Kibar site.

The UN watchdog's deputy director general Olli Heinonen, who led the delegation, has described his trip as a "good start" but has not given any details over the findings.

He said the visit was a "first trip" whose findings now had to be analysed.

Syria's top regional ally Iran has over the past two decades pushed forward with its own nuclear drive, which Tehran insists is only aimed at producing energy but the West fears could be used to make atomic weapons.

Israel is believed to be the sole nuclear weapons power in the Middle East, even though the Jewish state has never officially confirmed the existence of such an arsenal.