Zimbabwe's run-off presidential election on June 27 is very unlikely to be free and fair, a group of southern African ministers said on Thursday, in the strongest regional condemnation yet of pre-poll violence.

"There is every sign that these elections will never be free nor fair," Tanzanian Foreign Minister Bernard Membe told a news conference. He was speaking in Tanzania on behalf of a peace and security troika of nations from the Southern African Development Community (SADC).

Tanzania is also current chairman of the African Union.

Membe said he and the foreign ministers of Swaziland and Angola would write to their presidents "so that they do something urgently so that we can save Zimbabwe."

SADC is sending 380 monitors to Zimbabwe for the vote, in which President Robert Mugabe faces the biggest challenge to his 28-year rule from Morgan Tsvangirai, leader of the opposition Movement for Democratic Change (MDC).

Membe said their judgement on the conduct of the poll was based on evidence from 211 observers already inside the country.

Some of the observers saw two people shot dead in front of them on June 17, Membe said, without giving details.

Mugabe is accused by opponents, Western countries and human rights groups of orchestrating a campaign of killings and intimidation to keep his hold on the once prosperous country, its economy now in ruins. The MDC says at least 70 of its supporters have been killed.

Tsvangirai told Reuters Television on Thursday that drawn-out court proceedings against MDC Secretary-General Tendai Biti were part of the government's intimidation programme and this was affecting his run-off campaign.

"We spend time here, a lot of time which is unnecessary to attend to the court proceedings and therefore it affects our campaigning," Tsvangirai said at the Harare High Court, where Biti was due to appear on treason charges which carry a possible death penalty.

TERROR CAMPAIGN

A senior Western diplomat speaking in the region said the violence was spreading and had now taken on terror proportions.

"It's time really that we moved beyond calling this a campaign of violence. This is terror, plain and simple. This is a terror campaign that the joint operations command has launched weeks ago, it's too well organised, it's too well focused, it's too comprehensive, it's too completely political in its objectives to be anything else," the diplomat said.

He added that militias backing Mugabe's ZANU-PF party were now active in the capital Harare. "The atmosphere is violent. The violence is not abating, indeed it is spreading to areas where it has not historically spread before".

Mugabe lost the first round vote to Tsvangirai on March 29, but the latter fell short of the outright majority needed to avoid a second round, according to official results.

South African President Thabo Mbeki has urged Mugabe to cancel the run-off and negotiate a deal with the opposition, South Africa's Business Day newspaper said on Thursday.

Tanzania's Membe said both sides had indicated they would not accept defeat. "The statements being made by both sides ... are disheartening. Let us expect a lot of trouble to erupt in Zimbabwe after June 27."

He said the troika of SADC ministers were very concerned by the repeated arrest of Tsvangirai during the campaign.

ZIMBABWEANS 'HURTING'

"As Tanzania, we have told the government of Zimbabwe to stop the violence. We have told our observers not to be threatened, that they do their work without fear. People of Zimbabwe are hurting and it pains us," Membe said.

Mbeki met Mugabe and Tsvangirai separately in Zimbabwe on Wednesday to try to mediate an end to the violent crisis.

Business Day, a respected financial daily, quoted unnamed sources as saying Mbeki tried to set up the first ever meeting between the two men but Mugabe gave no firm commitment. It said Mbeki tried to convince them to form a unity government.

The South African leader did not comment after the talks.

Business Day said Tsvangirai agreed to meet Mugabe and said any run-off would be a farce.

The MDC said on Thursday it had made an urgent court application to overturn a state ban on media cover of its campaign.

Mbeki, who has led SADC mediation efforts in Zimbabwe, has been criticised for a quiet diplomatic approach that has failed to end a political and economic crisis driving millions of people into neighbouring states.

The Tanzanian statement on Thursday indicated increasing impatience in the rest of Africa and a willingness to abandon the discreet stance of the past.

Mugabe blames his foes for the violence and has threatened to arrest opposition leaders over the troubles.