Investigators have identified a Kenyan military officer as the father of one of the extremists involved in the attack on a hotel in Nairobi. Picture: Reuters/Njeri Mwangi

Nairobi — Kenyan investigators have identified a Kenyan military officer as the father of one of the extremists involved in the attack on a hotel and shopping complex in Nairobi this week.

There were conflicting reports on Friday about whether the extremist was among the five attackers who died in the assault, or helped to plan it and was among 11 people who have been detained by police.

Kenyan authorities say 21 people, including one police officer, were killed by the attackers. The al-Shabaab extremist group, which is linked to al-Qaeda and based in neighbouring Somalia, claimed responsibility.

The military officer, who is not believed to have been involved in the attack, was summoned for questioning about when he last saw his son and any other details, a senior police official said. The official spoke on condition of anonymity because he was not authorized to speak to the media.

The official said the suspect earlier was thought to be dead because his car was found at the dusitD2 hotel complex that was attacked on Tuesday. However, authorities now believe he may be among those detained, the official said.

"We are seeking further to know if he was at the scene and escaped, or he did not go there at all," the official said.

The Daily Nation, a Kenyan newspaper, said the alleged extremist's father is a sergeant with the Kenya Defence Forces. His mother was detained in Isiolo town and taken to Nairobi for questioning, the newspaper said.

Associated Press