By Steve Gutterman

MOSCOW (Reuters) - Russia will host world leaders at next year's G8 summit in the Black Sea resort of Sochi a few months after holding the Winter Olympics there, President Vladimir Putin said in a decree on Monday.

The decree published on the Kremlin website set Sochi as the site of the meeting of the leaders of the Group of Eight leading industrialized nations in 2014, when Russia will hold the rotating chairmanship of the G8.

Russia will spend more than 1.5 trillion roubles ($50 billion) of public and private funds to stage the Winter Games in February 2014, including extensive upgrades roads and other infrastructure, a senior official said last week.

"The reasons for choosing Sochi are obvious," state-run Itar-Tass news agency quoted Putin's spokesman Dmitry Peskov as saying. He cited the need to provide adequate infrastructure, ensure security and "make the work of the summit fruitful".

"The infrastructure being created in Sochi for the Olympic Games is practically ready and meets those requirements."

Most of the venues have been built from scratch in the city stretching from the shore to the Caucasus Mountains, which was awarded the Games in 2007, during Putin's previous presidency.

Putin appointed his chief of staff Sergei Ivanov to organize the G8 meeting, dismissing Moscow Mayor Sergei Sobyanin from the role. The decree gave no reason for the change, but Sochi is some 1,400 km (870 miles) south of Moscow.

There had been talk of holding the G8 summit at Skolkovo, a high-tech incubator being built just outside Moscow that has been championed as an innovation hub by Prime Minister Dmitry Medvedev, who was president from 2008-2012.

Putin said in December that Skolkovo was too close to Moscow and that it would not be completed in time for the G8 meeting.

Ivanov is a former defense minister with a security background and Putin has stressed the need to ensure security at the Olympics in Sochi near the violence-plagued North Caucasus provinces.

The decree gave no date for the G8 event, but summits of the group - whose chairmanship rotates among members the United States, Britain, France, Germany, Japan, Canada, Italy and Russia - are usually held in late spring or early summer.

Putin skipped last year's summit, hosted by U.S. President Barack Obama. Putin said was busy forming a government shortly after his inauguration to a six-year presidential term but the decision was seen as a snub against the United States.

($1 = 30.0180 Russian roubles)

(Editing by Alison Williams)