BBC Online :
Heavy fighting is taking place in and around the eastern Ukrainian town of Sloviansk, Russian and Ukrainian media report.
Ukrainian troops shelled the town early on Tuesday, Itar-Tass reported, with warplanes flying overhead.
One member of the security services was reported by local media to have been killed and 13 injured when separatists attacked posts near Sloviansk.
The interior ministry says separatist roadblocks have been destroyed.
For weeks, Russian-speaking eastern Ukraine has been the scene of deadly clashes between government troops and pro-Russian insurgents who have taken over key buildings across the region.
Interior Minister Arsen Avakov urged residents of Sloviansk to stay indoors while the assault against pro-Russian militants was in progress.
He said on his Facebook page that “an active offensive stage of the
counter-terrorist operation is under way”.
Military sources quoted by Itar-Tass say that while fierce fighting rages north-east of Sloviansk, on Tuesday the Ukrainian military was also concentrating its fire on nearby Semyonovka, where automatic fire could be heard in different parts of the village.
Separatists in the area claim to have destroyed a Ukrainian warplane, a helicopter and several tanks – but these claims could not be independently confirmed.
Itar-Tass says that there were also fierce clashes throughout Monday night in the town of Kramatosk, about 10km (6 miles) from Sloviansk.
It says that explosions and artillery fire were heard at the local airfield and three separatists were killed elsewhere in the area.
On Monday, hundreds of separatists assaulted a border command centre near the city of Luhansk.
Five militants were reported to have been killed and eight wounded when the centre came under sustained attack. Seven border guards were said to have been wounded.
As many as 500 pro-Russian gunmen are believed to have been involved in the assault.
Correspondents say the separatists have become more and more aggressive in their assaults on government-held positions as they try to obtain weapons and ammunition from Ukrainian forces.
