Image caption Roger Gower was tracking poachers in the Maswa Game Reserve in northern Tanzania

Tanzanian police have arrested three suspects over the death of a UK pilot working for a conservation fund whose helicopter was shot down by poachers.

Natural Resources and Tourism Minister Jumanne Maghembe told AFP news agency that those detained were co-operating.

Roger Gower, 37, had been flying near an elephant killed by poachers when his helicopter came under fire.

Prince William, who has long campaigned on wildlife conservation, was said to be "saddened" by the death.

The incident happened in Maswa Game Reserve, which borders the Serengeti National Park in northern Tanzania.

Mr Gower managed to land his helicopter, but died before he could be rescued, a Tanzanian MP and former minister for natural resources and tourism, Lazaro Nyalandu, said in a tweet.

Image copyright Tropic Air Kenya

A spokesman for Tanzania's national parks, Pascal Shelutete, said three elephant carcasses had been found in the area, indicating "that whoever shot the chopper down was on a serious illegal hunting spree".

He said such poachers could be "heavily armed with sophisticated military weaponry".

Mr Gower was originally from Birmingham and worked in London before moving to East Africa to work as a helicopter pilot.

His brother Max told the BBC: "He would not have gone anywhere near those poachers if he'd known that they were armed.

"As I understand it, he knew they were around but came across them by accident. He didn't really have enough time to evaluate the situation before they opened fire on him."

Max Gower also said his brother would be remembered as "very much his own man".

"He had a very strong moral compass. He just loved having fun, he couldn't be with his friends without making sure that everybody had fun."

'Appalling risk'

Prince William has campaigned for years against the illegal trade in animal parts, particularly elephant ivory and rhino horn, and has roles in the organisations Tusk and United for Wildlife.

Though he had never met Mr Gower, a spokesman for the Duke of Cambridge said: "The duke was saddened that yet another life had been lost due to poaching."

The Gower family have invited donations to a fund established in Roger's memory that will contribute towards anti-poaching efforts in Tanzania.

The Friedkin Conservation Fund, for which Mr Gower had been working, said the organisation had lost "a dear friend".

The charity's founder, Dan Friedkin, said: "We believe that Roger can best be honoured by redoubling our commitment to protect elephants and our priceless wildlife heritage.

"This tragic event again highlights the appalling risk and cost of protecting Tanzania's wildlife."

The Friedkin Fund says elephant poaching is "especially prevalent" in Maswa, with rangers encountering ivory poachers "on a fairly regular basis".