Russian forces have been instructed to resume their advance into Ukraine "in all directions" after Kiev refused to hold negotiations, the Russian Defense Ministry said Saturday.

All units were ordered to mount an offensive in accordance with the operation plan, Defense Ministry spokesman Igor Konashenkov said during a briefing Saturday.

Russian President Vladimir Putin on Friday ordered a halt to military operations in light of expected negotiations with the Ukranian leadership, local media reported citing Kremlin spokesman Dmitry Peskov.

The Ukrainian side said that Kiev refused to negotiate with Russia because the conditions proposed were "unacceptable," and were "an attempt to force the country to surrender."

Troops from Lugansk have advanced up to 46 km and captured the settlements of Schastia and Muratovo, while troops from Donetsk have advanced another 10 km from the frontline, according to the ministry.

The ministry also said Saturday that Russian Airborne Forces were protecting the Chernobyl nuclear power plant jointly with Ukraine's National Guard, according to local media.

Meanwhile, Deputy Chairman of the Russian Security Council Dmitry Medvedev said Saturday that the current sanctions against Russia could be a reason to review relations with all states that have imposed them.

Medvedev said this was a reason to end all dialogue with the West on strategic stability, and vowed that the sanctions wouldn't change Moscow's decision to conduct the ongoing military operation and protect Donbass.

He also noted that Russia may respond symmetrically to measures taken against Russian citizens and companies abroad, namely by seizing funds of foreigners and foreign companies in Russia.

Additionally, Russian aviation authorities said there would be a "mirror response" to the measures currently carried out by countries choosing to ban flights for Russian aircraft. Moscow vowed to close its airspace in retaliation.

During a phone call with his Turkish counterpart, Mevlut Cavusoglu, Russian Foreign Minister Sergei Lavrov said Moscow is ready for negotiations with "all constructive forces" to resolve the Ukrainian crisis.

However, the General Staff of the Ukrainian Armed Forces said Saturday on Facebook that the siege of Kiev is the primary purpose of Russia's offensive against Ukraine.

The department said that Russia plans to encircle and block Kiev to "demilitarize" Ukraine and force the Ukrainian leadership to change its political course on Russian terms.