Yemen's Islamic State-linked militants say they have killed a senior security officer in the southern port city of Aden.

The militants on Monday said in an online statement that they killed Col. Ali Saleh al-Yafie and posted photographs purported to show the killing in Aden's Mansoura neighborhood.

The statement could not be independently verified but it was posted on an IS website that has had similar claims in the past. It did not say when the Yemeni colonel was killed.

The IS-linked militants in Yemen and the country's al-Qaida branch, considered by Washington to be the most dangerous affiliate of the terror network, have exploited the chaos of Yemen's civil war to stage significant land grabs and expand their control in the south.