The US says it has killed senior Isis members in a ground raid in the eastern areas of Syria.

US Special Forces claim to have killed Abu Sayyaf, a lead figure in charge of oil and gas as well as financial operations for the group, according to a statement released by the US Department of Defense.

US defence officials said Sayyaf was an instrumental industry and finance figure for the group, who had raised money through black market oil and gas sales. Until July 2014, Isis had been yielding at least $1m per day from illicit sales of oil to Turkish and Syrian buyers, according to a number of estimates.

However since the US-led air campaign, many of the refineries used by Isis in Syrian deserts have be destroyed or damaged.

Meanwhile local media reports question the seniority of Sayyaf, who has been identified as Tunisian-born Nabil Saddiq Abu Saleh al-Jabouri.

According to a UK-based network, the Syrian Observatory for Human Rights, on Saturday, the group took control of the northern part of the ancient Syrian city of Palmyra, which it has been advancing on for three days.