HARARE (Reuters) - Zimbabwe's generals occupy no official posts in its ruling party, but analysts say they will play a crucial role in President Robert Mugabe's drive to stay in power.

The heads of the army and security forces are thought to have been key planners in an emerging strategy for Mugabe, 84, to fight back after elections a week ago that handed the former guerrilla commander his biggest defeat in 28 years of power.

Analysts say Mugabe is banking on these commanders to deal with any post-election violence while he deploys his political forces against opposition leader Morgan Tsvangirai, who says he won last week's vote and should be declared president.

In a multi-pronged strategy, the ruling ZANU-PF is also calling for a recount of the presidential vote and challenging enough seats in the parliamentary poll to reverse victory there by the opposition Movement for Democratic Change.

"It's difficult to get a clear picture ... but it is fair to assume that without their (the generals') support, Mugabe would not be going in this direction," said a senior Western diplomat.

"We have heard suggestions of splits in the top ranks, of divergent views on what is going on, but there is nothing on the ground to support that," he told Reuters. "I think Mugabe still enjoys and commands enough respect and loyalty to be able to count on them in times like these."

Defence Forces commander General Constantine Chiwenga and police chief Augustine Chihuri issued tough statements ahead of the poll backing Mugabe and denouncing both Tsvangirai and third presidential candidate Simba Makoni, a former finance minister. Like all other security chiefs, they are veterans of the guerrilla war against white rule in the 1970s.

Many see their backing for Mugabe as a formidable obstacle to Tsvangirai's Movement for Democratic Change, which has tried to reassure security forces that they have nothing to fear from a change of government if they remain "professional".

"The generals may have no positions in ZANU-PF, but they are part of the party and when their party is challenged they take part in efforts to defend it," said John Makumbe, a Zimbabwean political commentator and fierce critic of Mugabe.

"In terms of training and competence, they are very professional but in terms of politics, they are not," he said.

The MDC charges that the army has taken a clear political line as Mugabe over the years deployed soldiers to stop peaceful anti-government protests. Security force chiefs said they would not accept a Tsvangirai victory.

Mugabe honed his political skills in the 1960s as a backroom strategist in Zimbabwe's liberation struggle and an articulate public speaker, and has long matched political savvy with a healthy respect for military muscle.

Unlike in many African countries, Zimbabwe's army remained largely in the shadows following independence from Britain in 1980 -- a public image analysts say belied its role in keeping Mugabe's government afloat.

That low-key approach started to change in 2000 as Mugabe faced a rising challenge from the MDC, and the military is increasingly coming to the fore in this election as Mugabe uses army officers, liberation war veterans and youth brigades in a campaign he says will "bury" the opposition.

In the last eight years, the veteran Zimbabwean leader has hired more serving or retired military officers into his party ranks to help shape a political strategy against the MDC, which he calls a puppet of Western powers.

Mugabe has also appointed dozens of former army officers to key posts, including in the Central Intelligence Organisation (CIO), the prison service, the police force, and the judiciary.

Retired senior army and security commanders have taken positions in Zimbabwe's electoral commission, parliament, the cabinet and ZANU-PF's politburo and central committee.

Mugabe learnt how to look after the military in the 1970s while leading Zimbabwe's independence war from neighbouring Mozambique. Since independence, defence has stayed in the top three departments in annual government budget allocations.

Senior army officers drive luxury cars and many have been allocated large farms seized by Mugabe from whites under his controversial land reforms.

Critics say Mugabe cemented his relationship with the army when he allowed top commanders to make money from diamond deals during Zimbabwe's five-year involvement in the civil war in Democratic Republic of the Congo. Mugabe denies his men were involved in corruption or looting.

Mugabe has secured the support of an irregular force of independence war veterans through huge pension payouts and handing out farms seized from whites.

The army, war veterans and youth brigades militia played important roles in invading farms in early 2000.

They were also blamed for violence the opposition says helped ZANU-PF win parliamentary polls in that year, and Mugabe's re-election in 2002.

ZANU-PF militants were restrained from campaign violence this year, although their presence in the countryside intimidated opposition supporters.

A presidential runoff between Mugabe and Tsvangirai is expected to be different.

"For Mugabe, this election is a matter of prestige, a matter of principle because he truly believes that the MDC is a stooge party that must be stopped," Makumbe said. "He is a born dirty player."