Russian artillery chief Mikhail Matveevsky told a briefing that the 9M729 missile's maximum range is 480 kilometres (300 miles).

The Intermediate-Range Nuclear Forces treaty bans missiles with a range above 500 kilometres.

Russia has long denied it violates the treaty but Wednesday's briefing was the first time it has offered details of the missiles in question.

"The distance was confirmed during strategic command and staff exercises" in 2017, Matveevsky told an audience of journalists and military attaches.

The United States and Russia agreed to the INF treaty in 1987.

Last month Washington gave Russia a 60-day deadline -- which ends on February 2 -- to dismantle the missiles it claims breach the agreement or the US would begin the six-month process of formally withdrawing from the deal.

Russian Foreign Minister Sergei Lavrov has said Moscow is ready to work with Washington to save the agreement, after bilateral talks in Geneva on the INF this month failed to resolve the impasse.

Russian President Vladimir Putin has threatened to develop nuclear missiles banned under the INF treaty if it is scrapped.

He said in December he was open to the idea of other countries joining the deal or to starting talks on a new agreement.