WASHINGTON, Dec. 30 (Xinhua) -- The White House on Monday denounced the twin terrorist attacks on the Russian city of Volgograd in the past two days, voicing hope for "closer cooperation" with Russia in its security arrangements for the upcoming Sochi Winter Olympic Games.

　　"The United States stands in solidarity with the Russian people against terrorism," National Security Council spokeswoman Caitlin Hayden said in a statement. "The U.S. government has offered our full support to the Russian government in security preparations for the Sochi Olympic Games, and we would welcome the opportunity for closer cooperation for the safety of the athletes, spectators and other participants."

　　At least 10 people were killed and 10 more injured early Monday when a bomb went off in a trolley bus in Volgograd. The attack came one day after a female suicide bomber blew herself up at a railway station in the city, killing 17 people and injuring 45 more.

　　Russian President Vladimir Putin on Monday gave a directive requiring the country's anti-counterterrorism commission to step up measures and guarantee security in Volgograd and other regions, in addition to reporting to him on a daily basis about security situation across Russia and implementation of relevant security measures, according to information published via the website of the President of Russia.

　　In light of the deadly blasts in Volgograd, no extra security measures will be adopted for the Sochi Olympics slated for Feb. 7- 23, 2014, a senior Russian official said Monday.