As a small opposition party in Zimbabwe said four members were killed and many more people were injured the British Prime Minister, Mr Tony Blair, and President Thabo Mbeki of South Africa called for a large team of international observers to be sent as soon as possible to ensure Zimbabwe's elections were free and fair.
Speaking after talks in London, Mr Blair said he and Mr Mbeki shared a key goal over the Zimbabwe crisis - to return stability and prosperity to the country. Meanwhile, President Robert Mugabe told journalists attending an economic summit in GrandBaie, Mauritius, that British citizens would not be allowed to observe Zimbabwe's general elections on June 24th and 25th.
The clashes with ruling party members in north-eastern Mudzi district occurred late on Wednesday and early yesterday morning, Mr James Chitungo, the United Parties (UP) elections director said.
"We received information this morning that two of our members were murdered last night, and just now I have received a report that two more have been murdered this morning," Mr Chitungo said.
The UP is led by Bishop Abel Muzorewa, the former prime minister of the short-lived Rhodesia-Zimbabwe transitional government of 1979.
The four, who included a traditional chief, were the second group of UP members reported killed since political violence erupted in February, and they bring the total figure of people killed in the run-up to elections to 25.
The main opposition Movement for Democratic Change (MDC) has claimed the majority of those killed were its supporters.
Bishop Muzorewa described the killings as "an organised and ruthless campaign for the elimination of the opponents". "We know this is not just political violence from hooligans, but has been well blessed by the head of state," Dr Muzorewa said.
Mr Mugabe told journalists that he had advised the Commonwealth Secretary, Gen Don McKinnon, that the Commonwealth was welcome to send observers to the election as long as they included no British.