BERLIN, May 15 (Reuters) - There are Russian assets worth 3.95 billion euros currently frozen in Germany, according to a letter from the finance ministry seen by Reuters on Wednesday.

The figure includes assets of individuals and companies that were subject to sanctions following Russia's attack on Ukraine, as well as foreign assets of the Russian central bank.

"This sum is subject to valuation fluctuations," the ministry said in the letter, addressed to Markus Herbrand, a politician of Germany's pro-business Free Democratic Party.

In March 2023, the finance ministry referred to Russian assets worth 5.25 billion euros frozen in Germany. The letter, dated May 10, does not provide a precise breakdown or a reason for the decline.

The European Union wants to use interest payments on Russian assets to boost Ukraine's defence, a proposal supported by German Chancellor Olaf Scholz.

Finance Minister Christian Lindner is planning a new authority to better enforce sanctions and step up the fight against money laundering. However, discussions within the German coalition government have been stalled for months.

"Every delay in the relevant coalition negotiations only offers Russian money launderers opportunities to keep their assets safe," Herbrand said. ($1 = 0.9239 euros) (Reporting by Christian Kraemer, writing by Maria Martinez, editing by Christina Fincher)