Nairobi - Islamist militants al-Shabaab issued a warning against Somalis who frequent hotels, beaches and nightclubs in the capital Mogadishu, saying it will target men and women who engage in "immoral culture".Al-Shabaab frequently stages bomb and gun attacks in the capital - and especially around popular hotels - in its bid to topple Somalia's Western-backed government and impose a harsh version of Islamic law.Somalia, which descended into chaos after dictator Mohamed Siad Barre was ousted in 1991, is trying to rebuild after two decades of conflict and chaos.Improvements to the security situation in Mogadishu has led some Somalis to return from the diaspora, and they have brought with them habits of playing music into the night and swimming in Mogadushu's white sand Indian Ocean beaches."Let Muslims avoid going to the hotels where men and women misbehave," Sheikh Ali Jabal, al-Shabaab's leader for the capital region, said in a statement. "Anybody engaged in this immoral culture is seen as part of the enemies that invaded Somalia."Somali authorities had no immediate response to the threat.Al Shabaab's warning comes one day after its militants stormed an African Union base, about 90km south of the capital, where they say they killed 50 peacekeepers.The peacekeeping force, known as Amisom, called it a "heinous" attack, but has not released its own death count. Al-Shabaab often exaggerates the success of its attacks, and officials played down losses.