HARARE (Reuters) - Zimbabwe's ruling party expects a runoff election and is confident President Robert Mugabe will retain power, Deputy Information Minister Bright Matonga said on Thursday.

Brushing off signs that Mugabe is in retreat for the first time in 28 years of power, Matonga told Reuters results from an election in which the ruling ZANU-PF lost control of parliament for the first time showed it won the majority of votes cast.

The opposition Movement for Democratic Change won the constituency-based parliamentary poll but no results have yet been released for the vital presidential vote. MDC says its leader Morgan Tsvangirai has won based on its own tallies.

"From ZANU-PF's perspective, we are very confident that we've got the numbers, when it comes to a re-run, we're ready for that second round, and we are confident that President Robert Mugabe will win this time," Matonga said.

In an interview with Reuters Television, Matonga added: "We think, and it is my assumption...there may not be a clear winner of the presidential one (vote) and it points to a re-run."

Matonga's words seemed the clearest indication so far that Mugabe was preparing to contest an April 19 runoff against Tsvangirai.

Officials said on Thursday results were expected soon from the senate election. They say the presidential outcome will not be released until after that.

There has been no word on the presidential vote since last Saturday's elections, held after a severe economic crisis put Mugabe under unprecedented pressure.

The Senate has 66 seats, six of them appointed by Mugabe. It has the power to block legislation from the lower house.

The Zimbabwean constitution concentrates much power in the president and parliament has been seen in the past as a rubber stamp body.

Respected South African financial daily Business Day reported that Mugabe had admitted to family and advisers that he had lost and was weighing up whether to throw in the towel or contest a runoff against Tsvangirai.

RUNOFF?

The MDC says Tsvangirai has won the absolute majority needed to avoid a runoff but ZANU-PF and independent projections say he will fall short.

"Mugabe has conceded to his closest advisers, the army, police and intelligence chiefs. He has also told his family and personal advisers that he has lost the election," Business Day quoted an unidentified source as saying.

The newspaper said hardliners in Mugabe's government wanted him to see the contest through to the bitter end but personal advisers and his family want Mugabe to quit. Analysts believe he will go down fighting in a runoff.

Mugabe's aides have angrily dismissed the MDC's claim that it had won the presidential poll.

Mugabe, known for his fierce and defiant rhetoric, has not been seen in public since voting.

Final results of the election for parliament's lower house showed the MDC won 99 seats. ZANU-PF won 97 and a breakaway MDC faction won 10. One independent candidate won a seat. The outcome of the senate vote will be issued next.

All the signs are that Mugabe, a liberation war leader still respected in Africa, is in the worst trouble of his rule after facing an unprecedented challenge in the elections.

Widely blamed for the economic collapse of his once prosperous nation, Mugabe has faced growing discontent with the world's highest inflation rate of more than 100,000 percent, a virtually worthless currency and severe food and fuel shortages.

Hopes of a peaceful transition to power in Zimbabwe helped lift neighbouring South Africa's rand currency on Thursday as investors saw a positive impact on the region.

"I think that (Zimbabwe) certainly has the most influence on the rand at the moment," a Johannesburg-based trader said. "So there is potential for the rand to strengthen further if there is a peaceful transition."

Millions of economic refugees have fled Zimbabwe's misery into South Africa, many of them illegally.

Jonathan Moyo, Mugabe's former information minister who is now an independent in parliament, said authorities were not coping well with defeat. Security chiefs, who have said they would not accept an opposition victory, were anxious.

"You have generals who unwisely, or rather foolishly, told the world that they would only salute one candidate, who happened to have lost the election," he told reporters.

(Additional reporting by Nelson Banya, Muchena Zigomo, MacDonald Dzirutwe, Stella Mapenzauswa and Gordon Bell in Johannesburg; writing by Marius Bosch; Editing by Barry Moody)