US and the international experts in counter-terrorism have become increasingly concerned about security in Sochi
US and the international experts in counter-terrorism have become increasingly concerned about security in SochiReuters

The United States and Russia are showing cooperation in the hunt for four female potential terrorists, including a "white widow" and a wife of a dead terrorist, who is said to be already inside the heavily secured city of Sochi ahead of the Olympic Games.

Ruzanna Ibragimova, the 22-year-old widow of a jihadist killed by Russian security forces, is believed to have travelled from Dagestan to the Sochi area on Jan. 11 or 12.

A notice distributed to hotels in the area by Russia's internal security service said the widow is inside the city. "According to our information Ms Ibragimova may be used by the ring leaders of illegal armed groups from the organization of terrorist acts in the zone of the 2014 Olympics," The Telegraph has quoted the notice as saying.

Although the notice did not mention the scale of danger they might pose, the widows of fighters killed in the on-going conflict between Islamist separatists and Russian forces in the North Caucasus have been suicide bombers in the past.

US counterterrorism operatives are working with their Russian counterparts inside the massive, 1,500-mile security zone set up by Russian authorities, amid fears that next month's games could be targeted by terrorists. Sochi security officials are "looking for as many as four women," a source told FoxNews.com.

Concerns of threats by Islamist militants have led to the deployment of 40,000 police and security personnel to cordon off the entire city in a "ring of steel". Security concerns have been heightened at the wake of two suicide bomb attacks in the southern city of Volgagrad on Dec. 29 and 30, when 34 people were killed and 100 others wounded. The incident was followed by a number of other events in which Russia was seen countering terrorist threats.

The notice for Ibragimova is the first sign that a terrorist may have managed to infiltrate into the security zone, adding fears that many more might be already inside the city.

US and international experts in counter-terrorism have become increasingly concerned about security in Sochi in the wake of the recent attack and a call from Doku Umarov, the jihadist leader who has been described as Russia's Bin Laden.

According to Fox News, Ibragimova was spotted recently on the street outside the foreign ministry near Sochi. She is described as the white widow and is a well known member of a Chechen jihadist group.