Ukraine’s President Poroshenko says 1,200 prisoners held by separatist rebels have been handed over under the terms of a ceasefire agreement.

The two sides are meant to exchange all their prisoners of war in line with the accord struck on Friday.

The Ukrainian leader was speaking during a visit to Mariupol – the port city in the east which was threatened by rebels before the ceasefire took effect.

Poroshenko vowed to defend the city of half a million people with multiple rocket-launchers, tanks and air cover.