Sept 21 (Reuters) - Russia has modified the Kalashnikov AK-12 weapon its forces use in Ukraine to speed up firing and give soldiers more control over firing modes, RIA state news agency reported early on Wednesday, citing the weapon maker's president.

The AK-12 version, which entered service in 2018, will have its two-round burst cut-off disabled and will have a two-way control of firing modes, as well as an adjustable cheek rest, Kalashnikov Concern's President Alan Lushnikov told RIA.

"In the shortest possible time, we selected technical solutions, made a prototype and demonstrated it to representatives of the Russian Ministry of Defense," Lushnikov said.

He did not say when the modernised weapon will enter service, saying only that it is in the design documentation stage.

The AK-12 assault rifle developed by Kalashnikov, the general issue weapon of the Russian armed forces, has a caliber of 5.45 millimetres (mm) and an improved accuracy over its earlier versions, among others.

The Kalashnikov arms maker was sanctioned by the United States in 2014, the year Russia invaded and annexed the Ukrainian peninsula of Crimea. The EU and UK levelled their own sanctions against Kalashnikov Concern this year.

Russian President Vladimir Putin calls the invasion a "special operation" to demilitarise its neighbour, while Kyiv accuses Moscow of an imperial-style land grab to retake a pro-Western neighbour that shook off Russian domination when the Soviet Union broke up in 1991. (Reporting by Lidia Kelly in Melbourne; Editing by Michael Perry)