The UN Security Council on Saturday strongly condemned the "heinous and cowardly" murder of American journalist Steven Sotloff by Islamists and declared that ISIL must be defeated.

Sotloff, 31, was beheaded by militants from the Islamic State of Iraq and the Levant (ISIL)in a video released Tuesday, two weeks after the similar video of US journalist James Foley's killing was posted online.

"The members of the Security Council stressed again that ISIL must be defeated and that the intolerance, violence and hatred it espouses must be stamped out," said a unanimous statement from the 15-member council.

Council members added that "such continued acts of barbarism perpetraded by ISIL do not intimidate them but rather stiffen their resolve that there has to be a common effort amongst governments and institutions, including those in the region most affected, to counter ISIL, Al-Nusra Front and all other individuals, groups, undertakings, and entities associated with Al-Qaeda."

Sotloff, who also held Israeli citizenship, worked as a freelance reporter for various publications, including Time magazine, Foreign Policy and others, when he was kidnapped April 4, 2013 in Aleppo near the Turkish border.

US President Barack Obama outlined plans on Friday for a broad international coalition to defeat Islamic State extremists in Iraq and Syria.