Wellington - New Zealand Prime Minister Helen Clark urged Kenyan police on Friday to make a thorough investigation into the murder of photojournalist Trent Keegan, 33, in Nairobi.

The body of Keegan, who was born in New Zealand but had been freelancing in Ireland, was reported Thursday to have been found in a drainage trench off a main highway in Nairobi. He had serious head injuries.

A friend, Tim Gallagher, told Radio New Zealand that Keegan, who had been in Africa for two months, emailed him on May 16 saying he had been questioned by police and security guards from a safari park while investigating a story.

Keegan told him he was interrogated on a story he was writing about a tribe that was being kicked off its land to make way for a safari park.

"Trent apparently made a complaint to the chief of police, or whatever, and got an apology from them," Gallagher said. "He said in his email, 'Bloody corrupt down here, the police.'"

Clark issued a statement saying, "There is a lot of speculation in the media surrounding the death. The New Zealand government expects Nairobi police to conduct a thorough investigation into Mr Keegan's death. The investigation is expected to take some time."

New Zealand does not have a post in Nairobi and Clark said the foreign ministry was working through an honorary consul and its diplomats in Pretoria. (dpa)