A senior US senator raised concerns Wednesday about NATO arms deals with Russia, fearing the weapons could be used against American allies and that sales might one day expand to China.

Senator Richard Lugar requested a report by April 20 by the Congressional Research Service (CRS) to "examine the implications of several reported sales of military technology and equipment" by European NATO allies to Russia.

In a letter to the CRS, Lugar, the top Republican on the Senate's Committee on Foreign Relations, questioned the effect of such sales on NATO cohesion and pondered if the weapons would be used in simulated attacks on NATO territory.

"Reports indicate that approved or contemplated sales by our NATO allies include: French Mistral-class amphibious assault ships, assault vehicles, and infantry combat systems, German brigade combat trainers, and Italian armored vehicles," Lugar said in the letter.

"While NATO continues to foster a constructive relationship with the Russian Federation, these sales have raised concern in light of statements by Russian officials that certain equipment could be used for planning against US partners and allies."

Lugar went on to request that the CRS report back on a series of particular questions, including whether NATO should have a formalized system for discussing bilateral arms deals with Russia.

"Have such sales achieved any political benefits in the NATO-Russia relationship?" and "to what extent are our European NATO allies viewing the sales as a predicate to initiating similar sales to China?" Lugar asked.

The CRS is an advisory research body only and its reports do not constitute US policy.