* Russia's Finance Minister aims to boost extraction tax
* Wintershall says taxes make fields development unfeasible
MOSCOW, Oct 3 (Reuters) - Russia's proposed increase in mineral extraction tax (MET) has deterred Germany's Wintershall from taking part in a gas field project in the country, according to an official of Russian gas producer Gazprom , quoted by Interfax news agency.
Last year, Gazprom and BASF signed an agreement opening the way for Wintershall, BASF's oil and gas unit, to increase its stake in the Achimov layers of the Urengoy deposit in Siberia, where the German company is already producing gas with the Russian provider.
But Karen Oganyan, the head of Gazprom's tax policy department, said on Wednesday Wintershall may abandon the plan to develop the fourth and fifth Achimov beds at the deposit.
"The head of BASF's management board wrote a letter to Russian President Vladimir Putin saying that after the increase in the mineral extraction tax rate the project becomes unfeasible and the company is not interested in participation in it," he told the Federation Council, Russia's Upper House of the Parliament, according to Interfax.
A Gazprom spokesman declined to comment, while a spokesman for Wintershall was not immediately available due to a public holiday in Germany.
Last month, Russia's Finance Ministry proposed to increase the tax - albeit more slowly than previously suggested - by 12.5 percent for Gazprom and 15 percent for other producers starting from 2013.
Despite the slower pace of the rise in taxes Gazprom's Chief Executive Officer Alexei Miller has said it means his company will not be able to make investment decisions about the development of the Yamal peninsula and other strategic regions.
A Finance Ministry official on Wednesday said the ministry should present proposals on MET to the government by Nov.1. He said different rate of MET could be applied for certain fields, depending on costs related to gas extraction from the deposits.
(Reporting by Vladimir Soldatkin; Editing by Lidia Kelly and Anthony Barker)
Keywords: RUSSIA WINTERSHALL/