* Rosneft, Pertamina agree on Tuban refinery JV
* Pertamina may get stakes in two upstream projects in Russia
* Rosneft seeks to expand in fast-growing markets (Adds background, details on upstream projects)
MOSCOW, Oct 5 (Reuters) - Russian state oil company Rosneft and Indonesian state energy company Pertamina have agreed a refinery joint venture in the Southeast Asian country, which may also get stakes in upstream projects in Russia, Rosneft said on Wednesday.
Pertamina is seeking overseas producing energy assets as Indonesia's domestic oil output has been declining since the early 1980s. The company is also developing domestic processing facilities to cut fuel imports.
Indonesia, which rejoined OPEC last year, consumes 1.6 million barrels per day (bpd) and produces around 0.85 million bpd, according to a review conducted by BP.
Rosneft, which is expected to get a 45 percent stake in the 300,000 barrels-per-day refinery, wants to expand abroad, especially in a region dominated by OPEC producers from the Gulf.
The new Tuban refinery will have a crude processing capacity of 300,000 bpd and is targeted for completion in 2021.
Rosneft said that Pertamina could also get up to 20 percent in the offshore Northern Chayvo project off Russia's Pacific island of Sakhalin and up to 37.5 percent in the onshore Russkoye field in Siberia.
As well as its first venture with Russia, Pertamina is looking at energy projects in Iran, Saudi Arabia, UAE, Gabon, Kazakhstan and Azerbaijan, adding to its overseas assets in Malaysia, Algeria and Iraq.
Pertamina plans to upgrade four of its existing seven refineries, and develop at least two new oil processing plants by 2023, more than doubling its domestic capacity to 2.3 million bpd from 1 million bpd currently. (Reporting by Katya Golubkova in MOSCOW, Seng Li Peng in SINGAPORE and Fergus Jensen in JAKARTA; Editing by Christian Lowe and Louise Heavens)