KYIV, March 31: As per a previous agreement, Russia's Defence Ministry on Thursday announced ceasefire in Mariupol from 10 am local time (GMT: 07 am) and a humanitarian corridor was opened from Mariupol to Zaporizhzhia, via the Russia-controlled port of Berdiansk, to allow trapped civilians to evacuate from the besieged city.

"For this humanitarian operation to succeed, we propose to carry it out with the direct participation of the UN High Commissioner for Refugees and the International Committee of the Red Cross,” a Ministry statement said.

An earlier attempt at evacuating civilians from Mariupol had collapsed when Russians continued heavy shelling."

According to Mayor Vadym Boichenko, 160,000 people are trapped in the besieged port city. Convoys of buses have been sent to evacuate the civilians.

Mariupol has been the focus of Russian aggression since Kremlin began the invasion as the port city is key to Putin's plan to carve out a land route to peninsular Crimea from pro-Russian separatist controlled regions of Luhansk and Donetsk. Russia annexed Crimea in 2014.

Four million people have fled Ukraine since the invasion began on February 24, according to the latest UN refugee agency data.