A prominent gay rights activist in Cameroon has been found tortured and killed in his home, amid claims the authorities have systematically ignored similar attacks in the country.

The body of Eric Ohena Lembembe, an activist and journalist in the capital Yaoundé, was discovered by friends on Monday night. They had been unable to reach him by phone for several days.

Witnesses told civil rights organisation Human Rights Watch that they could see Lembembe's body lying on the bed through the window. When the police arrived and broke down the door, they found his feet broken, and his face, hands and feet burned.

The organisation said it was not yet clear whether the authorities would take action to bring the perpetrators to justice.

"The friends who found Lembembe's body have made a statement to the police, but at this point it's hard to tell whether the police are really investigating," said Neela Ghoshal from Human Rights Watch.

Lemembe was well known as a gay rights activist, as head of Camfaids, which campaigned for Aids sufferers in the central African country. Under the law in Cameroon – like many other countries on the continent – homosexuality is illegal and punishable by up to five years' imprisonment.

Lemembe's killing follows several attacks on the offices of human rights defenders in Cameroon, including those working for gay rights.

In his last blog post before he died, Lembembe – who recently contributed to a 55-page report on prosecutions of gay people in Cameroon – described attacks on gay and lesbian groups, and criticised the lack of action by the authorities to investigate and prosecute the perpetrators.

"It's extremely ironic and really sad that Eric seems to have been killed by the same violence he was speaking out against," said Ghoshal. "We don't know for sure yet whether he was killed because of his activism, but if he was, it proves his point."

Last month, Barack Obama caused controversy in many African nations when he used a tour of the continent to urge countries not to discriminate against gay people, saying: "I believe that everybody has to be treated equally."

Homosexuality is still illegal in most of Africa, with 38 countries criminalising consentual sex between homosexual adults, and four punishing homosexuality by death.

In some countries, there are moves to increase criminal sanctions for homosexuality. Nigeria, which shares a border with Cameroon, has introduced a bill against gay marriage, while Ghana has reacted furiously to statements by the Britis prime minsiter, David Cameron, linking aid to a country's stance on homosexual rights.

Last year in Cameroon one man, Roger Jean-Claude Mbede, was sentenced to jail for three years for sending a text message to another man saying "I'm very much in love with you." The case led gay rights group All Out to start a petition calling on the Cameroon president, Paul Biya, and the minister of justice, Laurent Esso, to reverse the sentence.

"We have urged Biya to make a public statement about the death of Eric Lembembe – we think the violence has got to the point where the head of state needs to speak up," said Ghoshal. "So far he hasn't, and there hasn't been any other public reaction from the government. Their silence provides the conditions for this kind of crime to continue."