Houthi rebels ignited fresh battles with local militia as the first boatloads of emergency medical aid arrived in the southern port city of Aden in Yemen, the Reuters news agency reported on Wednesday.

The embattled Arab state has been the scene of fierce clashes between the Houthi and the military in recent months.

The capital, Sanaa, and several key locations were taken by the Shiite militia last September in a bid to overthrow the government.

In Aden, dozens of people have been killed in weeks of clashes, and water and electricity supplies were cut off in central neighborhoods. Hospitals have also struggled to cope with the rising number of casualties.

The regional head of operations for the Red Cross, Robert Mardini, said the city was facing a humanitarian crisis:

Months of unrest forced Yemen's president, Abed Mansour Hadi, to flee his presidential compound in Aden last month for the Saudi capital, Riyadh, where he has remained ever since.

Street-by-street battles

Reuters also reported that Houthi fighters, believed to be backed by Iran, had left behind a trail of destruction in Aden, with witness accounts of bodies strewn across the streets and buildings razed to the ground by rocket fire.

The rebel push to seize the city was later reported to have been "partially repelled" and some northern neighborhoods cleared of the fighting.

Iran has denied arming the Houthis and condemned a Saudi-led offensive, which has pounded Aden and Sanaa with air strikes in a bid to stop Yemen's descent into full-blown civil war.

Tehran sent two warships to the Gulf of Aden on Wednesday, saying they would protect Iranian shipping in the region.

Regional threat in the Gulf

Saudi Arabia's leading role against the Houthi takeover has seen Yemen at the center of a regional proxy conflict between the Gulf's leading Sunni Muslim and Shiite Muslim powers, a struggle also prominent in Syria, Lebanon and Iraq.

The US, a major Saudi ally, said on Tuesday it would speed up arms supplies for the offensive and had increased intelligence sharing and planning coordination.

Elsewhere, Pakistan was debating a request from Riyadh for it to join the military operation.

Prime Minister Nawaz Sharif said he would defend Saudi Arabia's "territorial integrity" but had yet to define Islamabad's commitment to the Yemen crisis.

lw/kms (Reuters, dpa)