Earlier, the militants demanded 50 million dollars of bail.
According to Petrov, they threaten to kill Kochneva if the money is not paid.
Kochneva was abducted after she arrived in Syria to work as as a stringer in October 2012.
The Ukrainian government and Foreign Ministry are taking all possible measures towards the release of Ankhar Kochneva, a female journalist abducted in Syria, First Deputy Foreign Minister Ruslan Demchenko has said.
"We are systematically working on this issue, and are working with the Syrian side. But I would not like to comment on anything, as publicity may seriously damage the settlement of this issue. But believe me, the government and the ministry are doing their utmost for her release," he told Interfax.
Ukrainian journalist Ankhar Kochneva was abducted by gunmen of the Free Syrian Army in October 2012. The kidnappers threatened to kill her on December 13 if ransom in the amount of $50 million was not paid.
However, on December 17, 2012 Syrian rebels in an interview with TSN television claimed that the Ukrainian authorities were doing nothing to set Kochneva free.
The Ukrainian Foreign Ministry in turn, claimed that it was taking all necessary measures to release the journalist.
Russia, the United States and France, as well as international human right organizations, have called on the Syrian opposition to release the woman.
Voice of Russia, RIA, Interfax