Tensions between Somalia's moderate Islamist Ahlu-Sunna Wal-Jama'a group and the radical al-Shabab movement are mounting, following the murders of at least four Ahlu-Sunna clerics in recent weeks. 

Ahlu-Sunna Wal-Jama'a spokesman, Sheik Abdirahman Abu Yusuf condemned al-Shabab leaders, whom he says are sending out young assassins to target clerics in his Islamist organization. 

The spokesman says in the past week, al-Shabab killed Sheik Ali Afyare in the central Somali town of Galkayo and another cleric in Beledweyne, near the Ethiopian border.  Abu Yusuf says al-Shabab should never be referred to as an Islamist group because they commit un-Islamic acts.

Sheik Ali Afyare was the most prominent of four Ahlu-Sunna Wal-Jama'a religious leaders, who have been killed in Somalia in the past month.  Two other clerics were shot to death last month in a town outside of the capital Mogadishu.

Ahlu-Sunna Wal-Jama'a was known in Somalia as a religious brotherhood of moderate Islamists.  It had kept a low profile until early last December, when al-Shabab, listed as a terrorist organization by the United States, desecrated the graves of moderate Islamist clerics in the southern city of Kismayo.   At the time, the current president of the country, Sharif Sheik Ahmed, warned that the desecration was a politically motivated act, which could start a sectarian war.  

Ahlu-Sunna Wal-Jama'a declared a holy war on al-Shabab and since then, fighting between the two Islamic factions has been escalating. 

In January, al-Shabab lost control of two towns in the central Galgadud region to Ahlu-Sunna Wal-Jama'a.  Al-Shabab still controls most of central and southern Somalia.  But analysts say the loss of Dusamareb and Guriel was an unexpected blow and it caused the militant group to begin tightening their administrative and military grip on key towns.   

Al-Shabab has accused Ahlu-Sunna Wal-Jama'a of being funded and armed by neighboring Ethiopia, a charge Ahlu-Sunna Wal-Jama'a denies. 

Political battle lines have also been drawn.  Ahlu-Sunna Wal-Jama'a has given its full backing to President Sharif and his new U.N.-supported government of unity.  Al-Shabab calls the Somali leader a western puppet and says it will not stop fighting the government until Islamic or Sharia law is enforced throughout the country.

Implementing Sharia law in Somalia is something Ahlu-Sunna Wal-Jama'a also advocates.  But the two Islamic factions - one moderate, one hard-line conservative - have differing views on what kind of Sharia law should be introduced.  

Ahlu-Sunna Wal-Jama'a is associated with Sufism, a mystic, spiritual form of Islam considered heretical by al-Shabab.  Al-Shabab followers observe the traditions of the ultra-conservative Salafist/Wahabbist faction of Islam.

In recent days, al-Shabab angered Ahlu-Sunna Wal-Jama'a adherents by banning celebrations marking the birth of the Prophet Mohammed in areas under their control.  Al-Shabab calls the traditional Sufi celebration an un-Islamic ritual.

Ahlu-Sunna Wal-Jama'a spokesman, Sheik Abdirahman Abu Yusuf, says he believes the cleric killed in the city of Beledweyne was targeted because he had encouraged all Somalis to commemorate Prophet Mohammed's birthday.