The World Food Programme (WFP) has suspended food distribution in a district of Zimbabwe, alleging that supporters of President Robert Mugabe threatened their workers and seized donated grain.

The United Nations agency say activists from Mr Mugabe's Zanu-PF party distributed the food from a centre in Insiza District in an unauthorised manner.

Relief food distributions are not the place for any kind of political activity

World Food Programme statement

The UN action came a day after a human rights research organisation, the International Crisis Group, warned that food supplies were being used as a political weapon against opposition supporters in Zimbabwe where half the population are facing starvation.

The World Food Programme (WFP) said it would not tolerate the misuse of its resources for political ends and added that it was seeking urgent assurances from the Zimbabwean Government that such incidents would not happen again.

It issued a statement saying: "Relief food distributions are not the place for any kind of political activity.

"WFP will only distribute its food on the basis of need without regard to partisan affiliation."

Insiza - about 560 kilometres (350 miles) south-west of Harare - has been wracked by political violence ahead of an upcoming by-election which is being contested by Zanu-PF and the opposition Movement for Democratic Change (MDC).

Aid arguments

The Zimbabwean Government has accused Britain's High Commissioner of trying to ensure that food aid only goes to opposition supporters.

But the MDC said aid was being used against the opposition, with officials deliberately arranging distributions near MDC rallies to lure away starving voters who were then forced to chant ruling party slogans and surrender opposition party cards before being given food.

Human rights workers have reported similar incidents in recent months as hunger spreads throughout the country, with around 6.7 million people expected to need aid by December.

The WFP has blamed the hunger in Zimbabwe on a devastating drought combined with the government's policy of seizing productive land from white commercial farmers and giving it to blacks with little farming experience.

Government officials deny allegations their land redistribution plan has worsened the crisis.