Islamist insurgents have taken over about one-third of Mogadishu

The African Union has called on the UN Security Council to impose sanctions against Eritrea for supporting Islamist insurgents in Somalia.

It is the first time that the AU has called for sanctions against one of its own members.

The organisation has more than 4,000 troops in Somalia supporting the fragile transitional government.

Meanwhile, heavy fighting resumed in the Somali capital Mogadishu on Saturday, reports say.

Government forces launched a fierce counter-attack on Friday in a bid to regain control of parts the city taken by militants.

Move 'unprecedented'

The BBC's Martin Plaut says the AU's call for sanctions against one of its member states is an unprecedented development.

The AU is normally reticent in any direct criticism of its membership, our correspondent says.

A statement from the 53-member organisation said the UN Security Council should "impose sanctions against all those foreign actors, both within and outside the region, especially Eritrea, providing support to the armed groups".

The AU also calls for the imposition of a no-fly zone and a blockade of sea ports "to prevent the entry of foreign elements into Somalia".

The UN has already expressed concern about the flow of arms into Somalia, where hard-line Islamists of al-Shabab and Hisbul-Islam are battling for control of Mogadishu.

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Calls for an air and sea blockade of Somalia and for sanctions to be imposed on Eritrea have already been made by the East African regional grouping Igad.

With the whole of Africa now speaking with one voice the demand for sanctions can go forward to the UN, says the BBC's Elizabeth Blunt, in the Ethiopian capital Addis Ababa, where the AU is based.

Somalia's neighbours hope the international naval flotilla stationed off the Somali coast will use its warships and planes to enforce the embargoes, our correspondent says.

Somalia has been subject to a UN arms embargo for many years but weapons are still freely available in the Mogadishu weapons market.

Eritrea is already suspended from Igad and could now be barred from the African Union, analysts say.

Although Eritrea denies arming Islamist forces, insurgent leader Sheikh Hassan Dahir Aweys has reportedly claimed that the country supports their fight.

In an interview with Reuters news agency, he said: "Eritrea supports us and Ethiopia is our enemy. We once helped both countries but Ethiopia did not reward us."

Fierce fighting

Reports from Mogadishu said that at least 45 people were reportedly killed in Friday's fighting - more than half of them civilians - and nearly 200 wounded in one of the bloodiest days in Mogadishu for months.

Residents said there was sporadic gunfire on Saturday and feared the fighting would intensify following reports of militant reinforcements being brought in to tackle the government offensive.

Somalia currently has a moderate Islamist President, Sheikh Sharif Sheikh Ahmed, who was elected by a unity government in January as part of a UN-backed peace initiative.

However, Islamists have recently gained ground and control much of the south. Last week the transitional government also lost control of about one-third of Mogadishu.

Somalia has been mired in civil war for 18 years.