Southern warplanes strafed the airport at the capital, Sanaa, in the north, narrowly missing a Jordanian airliner on the tarmac. The airport was closed after the control tower was hit, probably in error by anti-aircraft units.
A French vessel was steaming across the Gulf of Aden towards Aden, to take off French and other European Union citizens. The British embassy was advising the approximately 800 British nationals in Yemen to 'keep their heads down.' The Foreign Office however is advising British and Commonwealth citizens in Aden to make use of the French evacuation plans.
International telephone lines were cut for long periods. A despatch by a Reuters correspondent, Al-Hag Assem Abdel Mohsen, from Sanaa, said the situation in Aden was not clear. 'Diplomats said they believed the airport in Aden, capital of former South Yemen, was badly damaged in a bombing attack and had been closed.
'In Sanaa, residents watched smoke rising near the city's international airport where people trying to flee by plane were turned away. One official in the capital said other planes also attacked the northern cities of Hodeida and Taiz.'
President Ali Abdullah Saleh declared a 30-day state of emergency. The Yemeni parliament decided to dismiss Vice President Ali Salem al-Baid and other southern leaders, blaming them for the outbreak of civil war.
In several areas northern and southern troops were engaged in fierce duels. The fighting, the most serious eruption of violence in four years, is rapidly pushing the country towards disintegration, or rather, to redivision. One of the main problems is that the two halves were never properly integrated. The two armies have separate command structures. Northern troops have been stationed in the south, and southern troops in the north, as a guarantee of mutual respect.
In July last year the chief of staff, Hussein Abdullah Bashiri, a northerner, resigned in protest at the lack of integration of the armed forces and at the policies of the Defence Minister, a southerner.
By the standards of other attempts at union between Arab states, such as the ill-fated United Arab Republic, created by Egypt and Syria, the coming together of North and South Yemen four years ago was a success.
Last year elections were held which were widely described as among the freest and fairest in a region where democracy commands little respect.
Rivalries emerged in the autumn. Vice President al-Beidh sulked in Aden and refused to attend cabinet meetings in Sanaa. He then went off seeking to promote his own foreign policy.
Although North Yemen was primarily traditional, and southern Yemen a Marxist state, the rivalries which have emerged have less to do with ideology than with the apportionment of spoils, and the reluctance of al-Beidh to relinquish power from his base in Aden. Yemeni society remains largely based on tribal groups.
The south, while smaller and poorer, is now fast exploiting recently found oil and gas reserves. This makes it less beholden to the north, and more inclined to go its own way.