The MDC believes its leader Morgan Tsvangirai has won outright
Zimbabwean police have arrested at least five officials for allegedly under-counting votes cast for President Robert Mugabe in last month's election.
Police said the election officials have been charged with fraud and criminal abuse of duty, accused of taking nearly 5,000 votes away from Mr Mugabe.
United Nations Secretary General Ban Ki-moon joined international calls for the urgent release of the results.
The opposition MDC is seeking a court ruling to force publication of results.
The Movement for Democratic Change (MDC) says its leader, Morgan Tsvangirai, won the election by a clear majority.
But Mr Mugabe's Zanu-PF is seeking a recount.
On Monday, High Court judge Tendai Uchena dismissed the Zimbabwe Electoral Commission's (ZEC) argument that his court did not have jurisdiction and set the case for Tuesday.
The judge said he would decide whether to treat it as an urgent case, before hearing the actual arguments.
If he decides it is urgent, he may rule on Wednesday.
"I think ZEC just wants to delay this whole thing," said opposition lawyer Alec Muchadehama.
The ZEC lawyer said the votes were still being verified, while the ruling party's demands for a recount was also delaying matters.
On Monday, Mr Tsvangirai visited regional powerhouse South Africa, where he met ANC President Jacob Zuma.
No word has emerged from those talks. Mr Mugabe's critics have long urged South Africa to take a tougher line on Zimbabwe's leader over allegations of human rights abuses.
Government ministers have said the arrested election officials were paid to falsify the election results.
They say the results posted outside polling stations showed more votes for Mr Mugabe than the forms forwarded to Harare for counting.
President Mugabe has ignored opposition calls to stand down
"That's absolute rubbish," MDC Secretary General Tendai Biti told the BBC's Network Africa programme.
"That's the desperate act of a dinosaur regime that has lost an election," he said.
Mr Biti said that anyone who worked for the ZEC was carefully vetted by the authorities.
He also urged the international community, and African leaders in particular, to press Mr Mugabe to accept defeat, saying otherwise there could be "bloodshed".
"They want to see dead bodies before they send Kofi Annan," he said, referring to recent violence over disputed elections in Kenya.
On Monday, two foreign nationals accused of working as journalists without accreditation were freed on bail and are due to appear in court again on Thursday.
Earlier, Mr Mugabe called on the black population to ensure white farmers did not regain seized land, reports say.
He said black Zimbabweans could not afford to "retreat in the battle for land", the Herald newspaper said.
"Land must remain in our hands. The land is ours, it must not be allowed to slip back into the hands of whites," he is quoted as saying.
At least 18 of Zimbabwe's few remaining white-owned farms have been invaded since Saturday, farmers say, raising fears of renewed violence ahead of a possible run-off in the presidential election.
In 2000, there were 4,000 white farmers working on much of the best land in Zimbabwe.
Just 300 now remain after a campaign of often violent land seizures, with the land redistributed to black farmers.
The government says the land reform programme was needed to right colonial era wrongs, when black villagers were evicted from the most fertile land.
The opposition says the farm invasions were a pretext to intimidate people in rural areas and has led to economic ruin.
This year's election campaign was relatively peaceful but the MDC fears that the new land invasions are a precursor to another campaign of violence.
Some say the occupations have taken place in rural areas, which voted for the opposition.