NAIROBI, Kenya - A Kenyan suspect arrested after two grenade blasts this week said in court on Wednesday that he took part in one of the attacks and is a member of the al-Qaida-linked Somali militant group al-Shabab.

The grenade blasts came after al-Shabab warned it would attack Kenya in retaliation for its military incursion into southern Somalia. Some though, questioned whether al-Shabab was behind the attacks given that it already has demonstrated it is capable of killing dozens of people in attacks on foreign soil.

Elgiva Bwire Oliacha, 28, also known as Mohammed Seif, pleaded guilty to nine charges, including causing grievous bodily harm to two people during Monday evening's blast at a bus stop where hundreds of blue-collar Kenyans were waiting to get a ride home.

An officer with the anti-terror police unit who brought Oliacha to court said authorities will bring more charges against him in court on Friday, including charges related to the grenade attack on a pub early Monday morning that wounded a dozen people.

The officer, who did not give his name because he is not authorized to speak with journalists, said that Oliacha is expected to plead guilty to all of those charges as well.

Chief Magistrate Gilbert Mutembei allowed police to continue holding the suspect for two more days to complete their investigations.

Oliacha, who was not represented by a lawyer, looked calm in court, smiling and laughing with journalists who questioned him. When asked if he had gone to train in Somalia with al-Shabab, he said: "I would not even give that information to police."

Oliacha was arrested Tuesday night by members of an elite paramilitary wing of the Kenya police at his house in a city slum.

Monday's two blasts came about a week after hundreds of Kenyan forces moved into neighboring Somalia to attack al-Shabab militants who the government blames for a string of kidnappings in recent weeks, including those of four Europeans, on Kenyan soil. One of the Europeans — a quadriplegic French woman — has since died in captivity. Al-Shabab, Somalia's most dangerous militant group, threatened to carry out terror attacks in Kenya in retaliation.

Police say Oliacha is a Kenyan and not ethnic Somali. During his arrest he was found with six guns, 13 grenades and hundreds of bullets in his house in a slum called Kayole in eastern Nairobi. Oliacha admitted to possession of the weapons in court on Wednesday.

Analysts have raised doubts as to whether al-Shabab was behind the Nairobi grenade attacks that targeted working-class Kenyans.

Given al-Qaida's preference for large-scale attacks, the twin blasts did not bear the hallmarks of a major, well-planned terror assault. A U.S. warning also had said likely targets would include shopping malls and night clubs where foreigners congregate.

Al-Shabab claimed responsibility for a suicide truck-bomb attack earlier this month which killed more than 100 in Somalia and the July 2010 suicide attacks in Kampala, Uganda which killed 76 people watching the World Cup final.

In July, experts monitoring U.N. sanctions against Somali and Eritrea, said the Kampala bombings "signaled a new and alarming trend, in which East African extremist groups inspired and mentored by al-Shabab, including the Muslim Youth Center in Kenya, might represent the next generation of extremist threats in East Africa and the wider region."