Ukrainian President Petro Poroshenko has revealed that he has ordered his military leaders to deploy further army units to prevent a potential offensive by Russian-supported separatists in eastern and southern cities, according to Interfax news agency.

In a statement after a meeting with security chiefs, Poroshenko confirmed that the units were to be deployed to protect Mariupol, Berdyansk, Kharkiv, and northern Luhansk.

"Several new [military] units and groups have been formed which will allow immediately for a possible offensive on Mariupol, Berdyansk, Kharkiv and northern Luhansk," Poroshenko said at a meeting of the Ukrainian national security and defence council.

Poroshenko ordered a meeting between his senior security chiefs after elections - deemed illegal by Kiev - were held by the separatists in the country's eastern regions, creating "people's republics" in Donetsk and Luhansk.

He said that he was committed to upholding the current peace process with the rebels - which includes a ceasefire agreed on 5 September - but has now proposed the removal of a law which gave special status to both Donetsk and Luhansk.

He had earlier stated that the rebel elections had jeopardised "the entire peace process" following a conflict which has taken the lives of more than 4,000 people since April.