Tanzania has denied claims by Kenyan tour operators that it started fires to delay the migration of wildebeest - a key element of the tourism industry.

The Kenyans say the fires dispersed wildebeest gathering to migrate from the Serengeti National Park to Kenya's Maasai Mara National Reserve.

Tanzania says fires are a common practice to allow fresh grass to grow.

It says the longer rainy season may also have led wildebeest to stay longer in the Serengeti.

Tanzania and Kenya are not unused to business wars and some of them can turn into diplomatic spats between the East African neighbours, our correspondent, Sammy Awami, says.

The migration was expected to happen last weekend, which is why the timing of the fires raised suspicions of sabotage, he says.

"They [Tanzania] are starting the fires intentionally... maybe with the hope that the tourists will stay longer in Tanzania," Kenyan tour operator Fankras Karema told the BBC's Anne Ngugi.

He said the delayed crossing had disappointed tourists and could affect business next year.

Dorina Makaya, spokeswoman for Tanzania's ministry of natural resources and tourism, said that early controlled burning was a common practice.

"The possible reason for delaying of wildebeest migration is water distribution, which appears to control the migration trend," she said. "We had a longer rainy season this year."

The annual migration of more than one million wildebeest draws tourists from around the globe.

The sight of wildebeest crossing the crocodile-infested Mara River, which straddles the border of both countries, has been described as a wonder of the world.

Both countries earn millions from tourists watching the annual spectacle.