Islamic militant websites say four leading members of Yemen's Al Qaeda branch have been killed in a suspected U.S. drone strike the previous day in an eastern Yemen province.

The four died in Yemen's southern port of Mukalla on the Arabian Sea, where rockets believed to have been fired by U.S. drones hit Al Qaeda militants based in the city's presidential residence on Monday, according to security officials.

The militant Aamaq outlet, affiliated with the Islamic State group -- an Al Qaeda rival -- says the four include Maamoun Hatem, reportedly an IS sympathizer. The three other militants were identified as Abu Anwar al-Kutheiri, Mohammed Saleh al-Gharabi and Mabkhout Waqash al-Sayeri.

The compound in Mukalla was recently captured by Al Qaeda's branch in Yemen, viewed by Washington as the terror group's most dangerous affiliate.