Nato warns of return to heavy fighting in Ukraine

Nato has warned of the risk of a return to heavy fighting in eastern Ukraine, as Kiev reported 30 attacks in the space of six hours, including howitzer fire, towards the port stronghold of Mariupol.

Although a ceasefire between Ukraine and Russian-backed fighters in Ukraine's eastern Donbas region has largely held since it was signed in the Belarusian capital of Minsk last February, violence has slowly escalated over the last month. Earlier this month pro-Russian rebels hit the town of Marinka, in what was the first major attempt of an advance since the first few days of the ceasefire.

"The conflict in Ukraine has already cost over 6,000 lives. Ceasefire violations persist. And there is still a risk of a return to heavy fighting," Nato secretary general Jens Stoltenberg told allied defence ministers at a two day meeting in Brussels today.

His colleague, the supreme allied commander for Nato, General Philip Breedlove also warned that Russia is training rebels to be "ready to do whatever mission is required of it in the Donbas."

"I don't think Mr Putin is done in eastern Ukraine," Breedlove told reporters today.

Stoltenberg also highlighted the recent buildup of Russian troops on the Ukrainian border as a concerning factor, while defence officials in Ukraine today reported another outbreak of violence in one of the biggest target zones for the pro-Russian rebels.

According to the press office of Ukrainian security operations in the east (ATO), several Kiev-held positions were attacked by heavy weapons yesterday afternoon with as many as 30 violations of the ceasefire occurring. However, it was the situation around Mariupol escalated most drastically.

The villages of Shyrokyne and Talakovka, which separate separatist-held territory from Mariupol both came under howitzer fire, while Shyrokyne was also attacked with portable Grad missiles, grenade launchers and small arms the ATO Facebook page reports.

Over the whole day the ATO recorded 43 instances of rebels opening fire, with other areas also coming under attack including frequent targets Shchastya and Peski both of which lay further to the north west. Shchastya is a strategic target in Luhansk region because of its large power plant, while Peski is close to Donetsk city airport - one of the region's most hotly contested landmarks since the start of the conflict.

According to the Ukrainian border service, over the last week Russia have also started sending in aircraft to monitor several areas of the border of the two countries.

"On 22, 23 and 24 of June, Russian Federation helicopters were spotted near the border of Luhansk region, Chernyhiv region and Kherson region. On June 23 they carried out a flight of three jets above annexed Crimea," the press secretary of the border service told local news source Ostrov.

Speaker of the ATO Andriy Lysenko reported no casualties today in his daily press conference, Ukrainskaya Pravda reports.