Aircraft from a Saudi-led coalition attacked Yemen's interior ministry in the capital, Sanaa, late on Friday and launched several other raids on sites in the heart of the city, residents and other sources there said.

The air raids by the coalition have intensified in recent weeks as a Gulf Arab ground force and fighters loyal to exiled President Abd-Rabbu Mansour Hadi prepare a campaign to recapture Sanaa, seized by Houthi fighters in September 2014.

Residents said about 10 air strikes were launched on the ministry building in the north of the capital, a police camp close to it and a military building.

The raids also targeted the presidential complex and a party building of former president Ali Abdullah Saleh which had already been destroyed in 2011, they said.

In Saada province, about 30 people were killed in various strikes in various strikes on Friday, a news agency controlled by the Houthis said.

The coalition began air strikes against the Houthis and their allies - forces loyal to Saleh - in late March after they pushed from their northern stronghold towards the southern port of Aden.

It is pushing ahead with an offensive in Marib, about 120 km east of Sanaa, trying to drive the Houthis out of the province in preparation for a push against the capital.

Sources within the coalition have said they are waiting for "zero hour" to launch a full attack on Marib which will signal the end of the Houthi rebellion, pan Arab television Al Arabiya said.-Reuters