Brown said the situation in Zimbabwe, where there is a tense political standoff in the absence of results from the March 29 presidential election, was "completely unacceptable".

"A message should be sent from the whole of the United Kingdom that what is happening in Zimbabwe -- failing to announce an election result, trying to rig an election result -- is completely unacceptable," Brown told parliament.

A Chinese ship carrying arms to Zimbabwe was turned away from South Africa last week after workers there refused to unload the weapons because of concerns that Zimbabwean President Robert Mugabe's government might use them against his opponents.

Other neighbouring countries refused to let the vessel dock.

"Because of what has happened in South Africa ... we will promote proposals for an embargo on all arms to Zimbabwe," Brown said, giving no further details.

Zimbabwe is among the issues due to be discussed by European Union foreign ministers at a meeting in Luxembourg next week.

Opposition leader Morgan Tsvangirai says he won the presidential poll. The ruling ZANU-PF lost its parliamentary majority in a parallel election, but a recount is underway in 23 constituencies.

Brown urged all African nations and the international community to "make their views known about the unfairness of this election".