Ngugi wa Thiong'o returned from exile last month

The author is now in hospital after his attackers, demanding money, tortured him with burning cigarettes.

An outspoken critic of former Kenyan governments, Professor Thiong'o only returned to Kenya last month after 22 years in self-imposed exile.

Police say they believe the attack is not politically motivated.

Politically charged writing

Police have launched a manhunt for the gang, who did not get away with much money as Prof Thiong'o mainly carried credit cards.

The apartments are close to central Nairobi police station

The BBC's Muliro Telewa in Nairobi said the attackers stormed their way into the apartment as Prof Thiong'o was seeing out a visitor.

His apartment is in a relatively secure part of the city - although Nairobi is often called "Nairobbery" by residents, such is its reputation for muggings and hijackings.

The writer was in Kenya on a month-long lecture tour, organised by his publishers, and has not made any politically controversial statements during his visit.

In an interview last weekend, Prof Thiong'o told Kenya's East African Standard newspaper that he felt humbled by his warm welcome in Kenya.

"I honestly thank Kenyans for making my return possible by ousting the former regime and secondly I am greatly humbled by the overwhelming and moving reception I have received from people across the country."

His politically charged writing led to his arrest in 1977 and he spent a year in detention without trial.

In 1982 he went into self-imposed exile in London, and then took up residence in New York where he taught comparative literature.

After his novel, Petals of Blood, which was written in 1977, he gave up writing in English to write in Kikuyu.

He argued that to provoke social change, works needed to be written in local languages and not those of the colonisers.