The USA extended the list of sanctioned Russian and Ukrainian individuals and institutions in an attempt to maintain pressure on Russia for Moscow's alleged support of separatists in Ukraine.

The administration of US President Barack Obama added on Thursday the names of 26 people and entities that will be subjected to economic sanctions, the New York Times informs.

The blacklists freeze the assets these individuals or entities may have in US jurisdiction and also prohibits Americans from doing business with them.

Some of the new actions are aimed at individuals or entities that US officials claim had been helping previously identified targets to evade sanctions.

Eight of the new targets are linked to to Gennady Timchenko, a billionaire Russian businessman, who is know for having close ties with Russian President Vladimir Putin.

Among the sanctioned entities are two arms manufacturing companies operating in Russia, including the Kalashnikov Concern, affiliate companies of Russian oil giant Rosneft and several organisations linked to one of the country's largest banks - Vnesheconombank.

Four officials, who served in the government of former Ukrainian President Viktor Yanukovych, as well as five operators of Crimean ports and one sea ferry operator were also added on the list.

An official of the US Treasury Department justified the measures as necessary to maintain the pressure on Russia for violating international law and escalating the conflict in eastern Ukraine.

Senior administration officials said that the new sanctions were a routine step rather than an escalation of economic sanctions aimed at pressuring Putin and the Russian government.

The West has expressed readiness to maintain the sanctions against Russia until fighting in eastern Ukraine is halted and the provisions of the Minsk ceasefire agreement are fulfilled.