Around 200 protesters gathered outside the Iranian embassy in the Yemeni capital on Wednesday, shouting slogans against what Yemen says is Iranian backing for northern rebels.

The group of 200 chanted slogans such as "No to the plot of Persian expansion" and "Yemen will remain free and independent" and called for the expulsion of Iran's ambassador.

Though the protest was organised by a non-governmental group, such events are unlikely to take place without official sanction.

Shi'ite Muslim rebels -- known as the Houthis -- have been locked in battle with government forces in north Yemen since August.

Yemen accuses Iranian figures of funding the group though it has stopped short of accusing Iran's government of backing the rebels, who say they are fighting social, economic and religious marginalisation by the Sanaa authorities and accuse Sunni neighbour Saudi Arabia of backing the government.

Iran has denied any involvement.

Saudi Arabia launched an assault on the rebels earlier this month after the Houthis staged a cross-border incursion that killed two Saudi border guards.

Yemen, an impoverished country of 23 million, also faces a separatist movement in the south while Saudi and Yemeni al Qaeda militants have regrouped on Yemeni soil and carried out attacks in the last two years.

Saudi Arabia, the world's largest oil exporter, fears the growing instability in neighbouring Yemen could turn into a major security threat for the kingdom by allowing al Qaeda to gain a stronger foothold in the impoverished country.

Global aid organisations have voiced deep concern at the escalation of the conflict in north Yemen, where the United Nations now says 175,000 people have been displaced by the fighting. – Reuters