Qatar dismissed reports of rivalry with neighbouring Saudi Arabia over efforts to end Syria's war, saying the two countries - the main Arab backers of rebel forces - had "the highest level of coordination".

Diplomats and opposition sources have reported strains between Qatari- and Saudi-backed groups within Syria's opposition National Coalition and have said the two countries have supported different armed groups on the ground.

The official Qatar News Agency said Foreign Minister Khaled Al-Attiyah, speaking at a public forum in Brussels on Saturday, "denied the rumours" about a dispute between Riyadh and Doha over Syria.

"We have the highest level of coordination with the Friends of Syria and in particular with Saudi Arabia," QNA cited Attiyah as saying.

Diplomats and opposition sources say that while Qatar supports the moderate armed groups also backed by Saudi Arabia and the West, it also has backed more hardline groups that seek to set up a strict Islamic state.

The reported differences have undermined rebel efforts to battle the forces of President Bashar al-Assad, opposition sources say.

Admirers of Qatari policy in Syria say Saudi Arabia tends to support the same armed groups as Qatar does.

The tiny but wealthy gas exporting country is under fierce pressure from Saudi Arabia, the dominant Gulf Arab power, to curb its support for Islamists of all stripes.

In an unprecedented move within the Gulf Cooperation Council of allied hereditary monarchies, Saudi Arabia, the United Arab Emirates and Bahrain recalled their ambassadors from Qatar on March 5, accusing Doha of failing to abide by an accord not to interfere in each others' internal affairs.

Qatar strongly denies interfering in Gulf Arab affairs and says its differences with its neighbours are instead to do with developments in the wider region - a reference to Egypt, where Saudi Arabia is helping the military-backed government and Qatar has voiced support for Islamist opposition forces.

Attiyah had dismissed demands by the three fellow Gulf states for changes to its foreign policy, calling its independence "non-negotiable".  - Reuters