MOGADISHU, Somalia Oct 4 (Garowe Online) - Reliable sources in Somalia's capital Mogadishu confidentially tell Garowe Online that insurgent groups waging war against the country's foreign-backed interim government are "on the verge" of open hostilities.

Relations between Islamic Courts fighters and al Shabaab gunmen worsened following al Shabaab's September threat to shoot down airplanes landing at Mogadishu's Aden Adde International Airport. [ READ: 5 killed in Mogadishu as airport bombed]

"The dispute is on the verge of war because there is no other visible solution," said an Islamic Courts source in Mogadishu who did not want to be named.

The source indicated that the biggest problem is al Shabaab's "opposition to peace" and the mortar raids on Mogadishu airport whenever a military or civilian airliner attempts to land.

Since September 16, when al Shabaab issued the threat, the airport has been targeted with mortars at least four times, leading to the government and its foreign allies' heavy shelling of civilian areas like Bakara Market in response.

However, a member of al Shabaab in Mogadishu accused the Islamic Courts of "wanting to destroy the [armed] struggle's successes."

"We will never accept the [Islamic] Courts' idea…our decision is to unite our strength so our goal of becoming the leaders of this country [Somalia] can be attained," said the al Shabaab source, who wished to remain anonymous due to the sensitivity of the matter.

Other Islamist sources in Mogadishu and Kismayo tell Garowe Online that the two insurgent groups – Islamic Courts and al Shabaab – have already taken steps to divide up the fighting ranks.

Al Shabaab reportedly expelled Islamic Courts fighters from the Jubba regions, including the port city of Kismayo, as the internal dispute worsened.

In response, the Islamic Courts "barred" al Shabaab from using Mogadishu's Bakara Market, which the Somali government has long accused of being a major base for insurgents.

Islamic Courts leaders, including Sheikh Sharif Sheikh Ahmed and Eritrea-based Sheikh Hassan Dahir Aweys, have publicly called on al Shabaab to stop the airport attacks.

Sheikh Sharif inked a peace deal with the Somali government in June, but Sheikh Aweys has opposed the agreement on grounds it provides no timetable for the withdrawal of Ethiopian forces.

Al Shabaab, however, has altogether rejected the peace deal and refused to recognize the exiled opposition group, which includes Sheikh Sharif and Sheikh Aweys as leaders.

In June 2006, when the Islamic Courts Union captured Mogadishu from U.S.-backed warlords, al Shabaab formed the core of the Islamists' fighting force.

The Ethiopian invasion later that year dislodged the Islamists from power, breaking up their ranks into small fighting units largely responsible for an ongoing insurgency.

In March this year, the U.S. government officially designated al Shabaab a terrorist organization and by May 1, al Shabaab's most well-known leader, Sheikh Aden Hashi Ayrow, was killed in an American air strike in central Somalia.

Source: Garowe Online