A Kenyan man pleaded guilty Monday to possession of six bombs including four suicide vests and being a member of al-Shabab, the Somali Islamist extremist group allied to al-Qaida that has threatened terrorist attacks in Kenya.

Abdi Majid Yassin Mohammed, 26, also known as Ali Hussein, had no defense attorney with him as he entered a guilty plea before magistrate Lucy Nyambura on charges that he was caught engaging in an organized criminal activity by being a member of al-Shabab, which has been outlawed in Kenya. The U.S. designated Al- Shabaab as a foreign terrorist organization in 2008.

Mohammed also admitted that he was in possession of the explosives, 12 grenades and 481 bullets but denied that he was in possession of four AK-47 rifles. His co-accused, Omar Abdi Ada, 24, also known as Salman Abdi, denied 10 charges against him including the weapons charges. The two suspects were unrepresented in court and spoke through interpreters. Ada is Somali.

Nyambura ordered Mohammed be taken for a psychiatric examination and be arraigned in court on Tuesday so that charges can read to him again.

The suspects were arrested Friday in a raid on a house in a residential area which police said disrupted the final stages of planning of a major terrorist attack. The house is in Eastleigh neighborhood in Nairobi where a large Somali community resides, earning it the name "little Mogadishu" — after Somalia's war-torn capital city.

After the raid police displayed suicide vests rigged with hundreds of metal ball bearings, two improvised explosive devices, also rigged with ball bearings, four AK-47 assault rifles, ammunition and 12 grenades. Police said the that the vests are similar to the type used in attacks in Uganda on crowds watching the soccer World Cup final on TV in July 2010, killing 76 people.

Al-Shabab claimed responsibility for the bombings in Uganda, saying it was in retaliation for Uganda's participation in the African Union's peacekeeping mission in Somalia. Al-Shabab has vowed to carry out terror attacks in Kenya after the country sent troops into Somalia in October to fight the militants.

Mohammed becomes the second Kenyan to admit being a member of the al-Shabab and taking part in terrorism. In October Elgiva Bwire Oliacha, also known as Mohammed Seif, was sentenced to life in prison after pleading guilty to taking part in a grenade attack that killed one person.

During his arrest Oliacha, 28, was found with six guns, 13 grenades and hundreds of bullets in his house in a slum called Kayole in eastern Nairobi