Nineteen died overnight in the north when Shia Houthi rebels clashed with government-backed militia.

Dozens of people were killed recently in an upsurge of violence in the area, straining a truce agreed in February.

In the south, militants ambushed and killed five soldiers in an area where al-Qaeda is active.

Government forces are now battling insurgents on two fronts.

The Houthis are confronting the mainly Sunni government and there are suspicions that Iran is supporting them, but both Iran and some independent experts dispute this.

In southern Yemen, the government has different problems, battling an insurgency believed to be supported by al-Qaeda.

There are growing fears that Yemen could descend into chaos and become a new base from which militants could launch attacks against the West.

A radical cleric based in the country is thought to have played a key part in the attempt on Christmas Day to blow up a passenger plane headed for the US city of Detroit.