MOSCOW, June 23 (Reuters) - Russia will work with the United States to track down cyber criminals, the head of the FSB security service said on Wednesday, a week after U.S. President Joe Biden and Russian President Vladimir Putin agreed to increase cooperation in certain areas. "We will work together (on locating hackers) and hope for reciprocity," the RIA news agency quoted FSB chief Alexander Bortnikov as saying at a security conference in Moscow. Deputy Foreign Minister Sergei Ryabkov told an investor conference that Russia had been "able to establish a very thorough and down-to-earth exchange with the U.S. side" on cyber security. Another senior ministry official said Moscow was awaiting an answer from Washington on starting consultations, TASS news agency reported. Biden told Putin at the summit that certain critical infrastructure should be "off-limits" to cyber-attacks after hackers seeking ransom money triggered the brief closure of a major U.S. oil pipeline network. read more Washington has said those responsible for some cyber-attacks in the United States have been working either directly for the Russian government or from Russian territory. The Kremlin has denied any state involvement. Putin and Biden also agreed to embark on negotiations to lay the groundwork for arms control agreements and risk-reduction measures. Defence Minister Sergei Shoigu said on Wednesday that Moscow had requested greater transparency about the deployment of missiles in Europe. He said Putin had proposed measures such as a moratorium on the deployment of intermediate- and short-range missiles in Europe to build mutual trust. The Kremlin has accused NATO of dismissing the proposals. "The overall situation in Europe is explosive, which requires concrete steps to de-escalate it," Shoigu said. "We are ready to work towards this." Russia"s relations with the West are at post-Cold War lows, strained by issues ranging from Moscow"s 2014 annexation of Crimea from Ukraine to allegations of Russian hacking of U.S. elections.