By Sami Torma

HELSINKI, April 17 (Reuters) - The author of a Western-backed plan to give Kosovo independence said on Tuesday that to alter it could make the territory ungovernable.

U.N. envoy Martti Ahtisaari last month recommended a form of supervised independence for Serbia's ethnic-Albanian dominated breakaway southern province.

The plan has the backing of the major Western powers but is rejected by Belgrade, and U.N. veto holder Russia has warned the West against imposing a solution in these circumstances.

"I think it is very dangerous to start tinkering with the plan," Ahtisaari told reporters, speaking in English, "because then we are dealing with ... whether Kosovo is going to be a place which cannot be administered properly."

Western diplomats say Moscow might try to water down the proposal or secure more autonomy for Kosovo's Serb minority.

Some Western analysts believe Serbia would settle for splitting Kosovo in two, taking control of the mainly Serb north, which already largely governs itself.

But the former Finnish warned against widening the divide.

"If it goes further, I think Kosovo becomes an unmanageable society," he said in Helsinki.

Serbia lost control over the territory to the United Nations in 1999, when NATO bombs drove out Serbian forces accused of atrocities in a two-year war with Albanian separatist guerrillas.

The West wants the U.N. Security Council to vote on Ahtisaari's plan by June, fearing unrest if Albanians are made to wait longer.

Russia and Serbia say they want more talks, and the Council will send a fact-finding mission to Belgrade and Pristina next week at Russia's suggestion before considering the blueprint.

But Ahtisaari, who mediated 13 months of fruitless Serb-Albanian dialogue in 2006 and 2007, said there was little support for more negotiations, and that Russia had enough experience of the issue to know more time would achieve nothing.

"I sincerely hope that when my present contract ends at the end of June, my services will not be required, and a decision has been reached," he said.

"If the decision will remain unclear, the situation in Kosovo will be difficult to handle ... If the status is open, then you can only speculate and it does not allow people to take a position on how they will plan their life."

AlertNet news is provided by