Russian President Dmitry Medvedev is hosting Pakistani President Asif Ali Zardari, Afghan President Hamid Karzai, and Tajik President Emomali Rahmon for a summit on regional security.
The four leaders are expected to issue a joint statement later today calling for greater international support for Pakistan's flood victims, believed to be some 20 million people.
The talks, which are being held at Medvedev's residence at the Black Sea resort of Sochi, are also expected to address drug trafficking in Afghanistan and terrorist threats to the region.
Medvedev, speaking the other three presidents, thanked them for their efforts in fighting terrorism and extremism.
"Combating terrorism and extremism is perhaps our most difficult task and I would like to say that I highly appreciate the efforts our three partners are making in fighting the terrorist threat," Medvedev said.
Medvedev is holding bilateral meetings with each of the visiting presidents.
Moscow has sought to regain regional influence it lost after the 1989 Soviet withdrawal following a 10-year war in Afghanistan.
Russia has said it will not send soldiers to Afghanistan, where it lost 15,000 troops in the Soviet-era war, but the Kremlin is holding out the prospect of supplying transport helicopters.
compiled from agency reports