Energy giants Rosneft and British Petroleum have agreed the biggest deal in years that will see BP buy $6bn worth of refined products from the Russian firm.

The agreement follows a deal earlier in 2013 that saw Rosneft sell oil worth $5.3bn (£3.3bn, €3.9bn) to BP.

Recently BP became Rosneft's second largest shareholder next to the Russian government, after Rosneft took over BP's Russian venture TNK-BP for $55bn in March 2013.

As well as BP, Exxon Mobil signed a flurry of deals with Rosneft to tap the Russian Arctic.

Over the past year, Rosneft also has sold large amounts of crude to trading houses such as Glencore, Vitol and Trafigura creating $11.5bn worth of pre-payment on the Russian firm's balance sheet.

Traditionally Shell has been first in line to appropriate Rosneft's oil and refinery products.

In the Pipeline

Rosneft also said in a regulatory filing it agreed to sell up to 3.2 million metric tons of fuel oil worth up to $2.6bn to BP Singapore between November 2013 and December 2014.

Rosneft will also sell BP up to 1.44 million metric tons of diesel worth about $1.77bn, and up to two million metric tons of fuel oil worth around $1.62bn.

The deal also includes up to 60,000 metric tons of naphtha estimated at $65m.

The deals come only months after Rosneft hired a former BP employee Marcus Cooper in May 2013.