UNITED NATIONS, April 14. /ITAR-TASS/. Yuri Sergeyev, the Permanent Representative of Ukraine at the UN, will take part in a UN Security Council's meeting on Ukraine if it is held in an open-door mode, an informed diplomatic sources at the UN Headquarters told ltar-Tass on Sunday.

"The format of the meeting has not been determined so far. Consultations on that score are being continued. If a decision is made to hold the meeting in an open-door mode, Ukraine's UN Ambassador will address those present. Otherwise, his participation in the (UNSC) meeting is unlikely," the source said.

An official at the RF Mission at the UN told Itar-Tass earlier that an urgent meeting on the situation in Ukraine's south-east was scheduled for 20:00, New York time. Originally, it was planned that the meeting would be held in a closed-door mode.

Russia's Foreign Ministry announced Sunday that it '"is bringing up the issue concerning the crisis situation in Ukraine's South-East for an urgent consideration by the UNSC and the Organization for Security and Cooperation in Europe (OSCE)".

"The development of the situation in Ukraine's South-East is acquiring an utterly dangerous character," the Ministry's announcement points out.

The Ministry warned Kiev againdt using armed forces in south-eastern regions of thr country and urged it "immediately to launch a truly nation-wide dialogue with an equal participation of all regions in the interests of effecting a radical constitutional reform as soon as possible".