BERLIN (Reuters) -Germany is set to approve close to 400 million euros ($450 million) in additional military aid to Ukraine, according to a finance ministry letter seen by Reuters on Thursday.

The funds are in addition to around 8 billion euros budgeted for Ukraine in 2024.

Germany is Ukraine's biggest supporter in Europe in terms of military aid. Ukraine has been backed by arms from its allies but is worried that support may drop as the war grinds on.

"In view of the continuously deteriorating military situation in Ukraine, there is a serious risk that Ukraine, without significantly increased material support, could be defeated in its defence campaign," the letter said.

Following a request by the defence ministry, the finance ministry in the letter is asking for the approval of the extra expenditure from the budget committee of the lower house of parliament.

Carsten Klein, member of the budget committee for the Free Democrats (FDP), welcomed the request for funds, saying that it showed Ukraine could rely on Germany's support.

"Ukraine urgently needs additional military material and equipment to defend its freedom and our values," Klein said.

The need for funds must be satisfied immediately to implement the measures in 2024 so they can have an impact during the remainder of the year, the finance ministry said.

The funds will be used to buy ammunition, fighting vehicles, drones and protective equipment, among other items.

The unplanned need for around 397 million euros has only become clear in the last few weeks, so it meets the constitutional and budgetary requirements of an unplanned need, the letter said.

If the budget committee approves the additional funds next week, the total amount of German military aid for Ukraine in 2024 will go up to 8.4 billion euros.

German aid to Ukraine will be cut to 4 billion euros in 2025, according to the draft of the 2025 budget, as the country hopes Ukraine will be able to meet the bulk of its military needs with the $50 billion in loans from the proceeds of frozen Russian assets approved by the Group of Seven.

($1 = 0.8986 euros)

(Reporting by Maria Martinez; Editing by Thomas Seythal and Conor Humphries)