Tanzanian police have arrested three men after a British pilot was killed when gunmen opened fire on his helicopter as he tracked suspected elephant poachers, a minister said Sunday.

Roger Gower, 37, was killed on Friday when his helicopter crashed after it was attacked during a patrol of the Maswa Game Reserve in northern Tanzania, close to the world famous Serengeti National Park.

"The suspects are in the hands of police," Natural Resources and Tourism Minister Jumanne Maghembe told AFP.

"They are cooperating, and soon more people making up the poaching gang will be netted and brought to justice."

Gower's South African colleague, safari guide Nicky Bester, leapt out of the helicopter midair as it crashed and was injured, according to a spokesman from Tanzania's National Parks, Pascal Shelutete.

"Three elephant carcasses that were found indicated that whoever shot the chopper down was on a serious illegal hunting spree," Shelutete said, adding such poachers can be "heavily armed with sophisticated military weaponry".

Photographs of the crashed helicopter show twisted metal, as well as apparent bullet holes in the fuselage, and smears of blood on the pilot's seat.

- 'Cruel criminals' -

It was not immediately clear if Gower was killed by the gunshots or when the helicopter crashed.

"The suspected poachers shot the helicopter which was on surveillance at a remote game reserve," Maghembe added. "This is a sad incident. We will continue with the war against poachers... these are cruel criminals."

The wildlife charity Gower worked for confirmed his death.

"Roger was killed while piloting a helicopter during a coordinated effort with the Tanzanian wildlife authorities to track down and arrest active elephant poachers," said a statement from Dan Friedkin, chairman of the Friedkin Conservation Fund.

"In the course of this action, the poachers fired upon the helicopter and Roger was fatally wounded."

Conservation officials appealed for help in catching the culprits.

"These people killing elephants in our conservation areas live in the neighbourhood, and those with information should come forward," Shelutete added.

"We all need to work together to end the killings of elephants and people fighting poaching."

Ivory is sought out for jewellery and decorative objects and much of it is smuggled to China, where many increasingly wealthy shoppers are buying ivory trinkets as a sign of financial success.

It is estimated that more than 30,000 elephants are killed for their tusks every year.

The international ivory trade was banned in 1989, but one-off sales of ivory stockpiles have since been permitted and trade in old ivory is also allowed, giving criminal smugglers cover for their illegal trade.

Neighbouring Kenya, which like Tanzania relies on elephants as a key draw for tourists who provide a massive boost for foreign earnings, announced earlier this month it will set fire to its entire remaining stockpile of ivory.

The fire of 120 tonnes, expected in April, will be eight times the size of any ivory stockpile destroyed so far, with tusks from several thousand elephants.