BRUSSELS, September 23. /ITAR-TASS/. The monitoring mission overseeing the ceasefire in Ukraine's war-torn south-east is being strengthened by 25 more observers each week, a European Union official said on Tuesday.

Teams from the Organization for Security and Cooperation in Europe (OSCE) are being strengthened by experienced specialists to monitor how the ceasefire is being implemented, said Gunnar Weigand, director of the EU Department for Eastern Europe and Central Asia.

The full strength of the mission teams will be increased by six times, taking it from 80 monitors to about 500, according to OSCE Secretary General Lamberto Zannier.

OSCE observers registered only isolated instances of the use of weapons over the first days since the signing in Minsk of a memorandum on implementation of the ceasefire regime in Ukraine’s embattled east, the OSCE said in a statement on its website.

Buffer zone in south-east Ukraine

The buffer zone in eastern Ukraine will be divided into five sectors to be observed by OSCE’s about 350 inspectors, Russia’s Ambassador to the Organisation Andrei Kelin told ITAR-TASS on Monday.

“The plan to divide the zone into sectors is in place: in Luhansk and in Donetsk will be working 90-100 inspectors in every city; in Kramatorsk, Mariupol and Antracit — 50 in each city," he said.

The parameters of the security area were negotiated September 19 in Minsk at the session of the contact group on Ukraine with participation of representatives from Ukraine, OSCE, Russia and the Donetsk and Luhansk people’s republics. The agreements were set in a memorandum on the implementation of paragraphs of the protocol upon the results of the contact group’s consultation (September 5) regarding the steps aimed at the implementation of the peace plan in eastern Ukraine.