Yemen crisis: Fighting intensifies in Aden

Fighting in the Yemeni city of Aden has intensified as Houthi rebels try to seize the key government stronghold.

Concern is growing over the number of casualties after heavy clashes between local militia fighters and rebel forces.

Witnesses have reported bodies lying in the street after intense rebel shelling and sniper attacks.

The fierce fighting has continued despite seven nights of airstrikes by a Saudi-led coalition.

The Houthi rebels, supported by troops loyal to the former President Ali Abdullah Saleh, have reportedly advanced deeper into Aden.

Last week the rebels appeared to be hours from overrunning the city. This forced President Abdrabbuh Mansour Hadi to flee to Saudi Arabia and spurred it to begin airstrikes.

The BBC's security correspondent Frank Gardner, in Riyadh, says that if reports of rebel tanks entering the centre of the southern port city are confirmed, then the rebels will have consolidated their grip on the most important parts of Yemen.

Where does the Saudi offensive go next?

Civilian deaths

As the fighting continues, civilians have been at the centre of concern over casualties.

A spokeswoman for the aid agency Medecins Sans Frontieres (MSF) told the BBC that its hospital in Aden had received more than 500 injured people from all sides in the conflict over the last two weeks.

Coalition spokesman, Gen Ahmed Asir, told the BBC "it was a hard task to target" the rebels.

The coalition was "using all intelligence resources to make sure they are not hitting the wrong target. We do not hit any target without making sure it is a Houthi or troops loyal to former President Saleh," he said.

The UN has also expressed alarm at the rising number of civilian deaths in Yemen.

Factory blast

President Hadi had taken refuge in Aden after the Houthis took full control of the capital Sanaa in January and placed him under house arrest.

On Wednesday, at least 35 workers were killed by a blast at a dairy factory in the Red Sea port city of Hudaydah.

There were conflicting reports about the cause of the overnight explosion but witnesses said coalition aircraft hit warehouses belonging to the factory.

The latest violence comes as dozens of Yemenis are reported to have crossed the Gulf of Aden in small boats to get to Somalia and Djibouti to escape fighting and airstrikes on the city of Taez.

The arrival of the Yemeni refugees reverses a decades-old trend in which thousands of Somalis have sought sanctuary in Yemen to escape their own country's violence.

The Houthis have said their aim is to replace President Hadi's government, which they accuse of being corrupt.