Britain on Monday led EU nations in condemning moves by Zimbabwe's President Robert Mugabe to take control of key ministries in defiance of a power-sharing deal with opposition parties.
British Foreign Secretary David Miliband said the European Union would "play no part in supporting a power grab by the Mugabe regime."
"It is important that there is an international united response that says that the results of the elections (earlier this year) need to be respected and a power grab will not be respected," Miliband told reporters at EU talks.
Miliband said he hoped South Africa's former president Thabo Mbeki can mediate a solution that will allow opposition groups to share power with Mugabe, as was agreed in September. EU ministers were to issue a statement urging Mugabe and opposition leader Morgan Tsvangirai to work out their differences and ensure they share power. The draft statement said it was urgent for both to agree on a new government of national unity to push forward reforms and to stop the deterioration of the humanitarian crisis in Zimbabwe.
Tsvangirai on Sunday threatened to pull out of the national unity government if Mugabe refused to cede control of the defense, home and foreign affairs, justice, mining and land ministries. Mugabe's party allocated only minor ministries to Tsvangirai's party, which won a slight majority in parliamentary elections in March.
Mugabe's party maintains that Mbeki only needs to mediate over one outstanding ministry finance and claims all the others are settled.
The EU has said it will keep sanctions against Zimbabwe until a power-sharing government is in place and it has met international demands for economic and political reforms, including better human rights.
The EU decided in July to increase sanctions against Mugabe's supporters to keep up the pressure on him.
The EU has blacklisted 172 people linked to Mugabe's government and four companies believed to financially support Mugabe and his ZANU-PF party. That list also includes Mugabe himself and members of his Cabinet, under measures passed in 2002.
All those on the list are subject to a travel ban and assets freeze.
The bloc also has frozen aid projects in Zimbabwe and imposed an arms embargo.