Nairobi, Kenya (CNN) -- Al-Shabaab, a hard-line Somali rebel group that is on the U.S. government's terror watch list, has threatened to attack neighboring Kenya, according to an online audio recording.
On an Al-Shabaab Web site, men chant in Kiswahili, the national language of Kenya, saying, "We will reach Nairobi. When we arrive, we will hit until we kill." A taped message in Arabic follows, thought to be by Abu Zubeyr, Al-Shabaab's commander in Somalia. The speaker of the message threatens those he calls infidels, throughout the world.
It would not be the first threat by Al-Shabaab toward Kenya. Many analysts say Kenya is vulnerable to attack by the Islamic group, which is trying to overthrow the weak transitional government.
The threat follows heightened tensions between the Kenyan government and Somalis living in Kenya over the past month. Kenya recently rounded up and arrested several hundred Somali immigrants and refugees living in a mostly Somali neighborhood. And earlier this month, Muslim protesters clashed with police after Friday prayers, leading to one death and extensive property damage.
Muslim human-rights groups in Kenya have called for protests in support of cleric Abdulah Ibrahim el-Faisal, whom Kenya declared an unwanted person and deported earlier this month. The Jamaican-born Muslim cleric was previously jailed in Britain for inciting murder and racial hatred. But Kenya's efforts to deport him failed. He was then arrested on return to Kenya, further outraging some Muslim leaders.
Alfred Mutua, Kenya's government spokesman, has since said that el-Faisal has successfully been deported. However, the government has given mixed signals as to whether he has actually left.