MOSCOW (AP) — Russia's Kremlin-controlled lower house of parliament on Tuesday approved legislation that toughens punishment for soldiers breaching their duties, in an apparent effort to boost discipline in the ranks amid the fighting in Ukraine.

The set of amendments to Russia's Criminal Code that was quickly endorsed by the State Duma introduces severe punishments for failure to follow orders, desertion or surrendering to the enemy. The bill now needs to receive the upper house's approval and then be signed by President Vladimir Putin to become law — steps that are considered to be formalities.

Under the new legislation, deserting a military unit during a period of mobilization or martial law would be punishable by up to 10 years in prison, compared with five years under the current law.

Those who voluntarily surrender to the enemy will also face a prison term of up to 10 years, and those convicted of looting could be handed a 15-year term.

Another amendment introduces a prison sentence of up to 10 years for those who refuse to go to combat or follow an officer's order.

The passage of the new legislation follows media reports alleging that some Russian soldiers in Ukraine have refused to go into combat and tried to resign from service.

Unlike Ukraine, which conducted a broad mobilization with the goal of reaching an active military of 1 million fighters, Russia has continued to rely on a limited contingent of volunteers.

Some nationalist politicians have called for a mobilization to beef up the ranks, but the Kremlin so far has ruled it out.