Moscow, Dec 19 (IANS/RIA Novosti): The Russian presidential human rights council has demanded that Syrian militants immediately release Ukrainian journalist Ankhar Kochneva.

The 40-year-old journalist Kochneva's kidnappers have reportedly threatened to kill her if their demand for a $50 million ransom is not paid by Thursday.

On Tuesday, Syrian rebels delayed her execution, Ukraine's 1+1 TV channel reported citing a commander of the Free Syrian Army.

The TV channel broadcast a video statement by Abu Jandal, an FSA commander, who said the rebels expect Ukraine to meet their demands.

"We consider the abductors' actions to be absolutely illegal and immoral, and urge everyone who has any influence on them to do all it takes to save Ankhar Kochneva," the council said in a statement posted on its website.

The journalist went missing in early October as she travelled to the city of Homs.

Kochneva, known as an expert on Syrian affairs, has been in Syria since the start of the conflict. An outspoken supporter of President Bashar al-Assad, she was freelancing for several Russian media outlets, including the NTV, RenTV and RT channels and the Utro.Ru news portal.

After she was kidnapped in October, she appeared in a video posted on YouTube in which she "confessed" to working for Russian intelligence. Her captors claim Kochneva was armed and had acted as an interpreter for Russian officers.