In his first act since taking office last week, the new Guatemalan president, Alfonso Portillo, has begun a big shake-up of the country's armed forces by appointing a colonel as the defence minister.

The appointment of Juan de Dios Estrada Velasquez will force the retirement of twenty more senior-ranking officers, including a number of generals accused of human rights abuses during the Guatemalan civil war.

Mr Portillo was elected last month, promising to reform the armed forces and solve the killing of a prominent Roman Catholic bishop two years ago -- moves that on Tuesday were welcomed by the United Nations Secretary-General, Kofi Annan.

Correspondents say the appointment of a moderate to head the armed forces is part of Mr Portillo's attempts to distance himself from his political mentor, the country's former military ruler, Efrain Rios Montt.

From the newsroom of the BBC World Service