Seven Ukrainian troops and as many as 300 pro-Russian rebels were killed in overnight fighting in Ukraine's restive east, an official said Friday, as clashes between government forces and pro-Russian rebels flared before Ukraine's Interior Ministry announced a weeklong unilateral cease-fire would begin later in the evening.

Insurgents who want to split from the government in Kiev were operating tanks in the region — a particular sore point for Ukraine, which accuses Russia of letting the vehicles and other heavy weaponry cross their border.

Vladislav Seleznev, a spokesman for Ukrainian forces in the east, said that in addition to the deaths, 30 troops were injured in fighting near the village of Yampil in the Donetsk region.

The figures for the scores of dead pro-Russian separatists could not be independently confirmed, though a rebel commander said Thursday that the rebels sustained "heavy losses" when they were outgunned by government forces backed by heavy armor, Reuters reported.

The violence comes shortly before the publication of a presidential peace plan, of which the unilateral cease-fire was an expected component.

Ukraine's Interior Ministry said in a statement Friday that the weeklong cease-fire would give pro-Russian rebels a chance to disarm should they be inclined.

"Today, on June 20, the cease-fire should begin. It will last through June 27," Ukrainian President Petro Poroshenko was quoted in the ministry's statement.

He discussed the details of his peace plan on the phone Thursday with Russian President Vladimir Putin. Poroshenko's office said he emphasized the need for introducing effective border controls and quickly releasing hostages seized by the rebels.

Poroshenko has said the plan will include amnesty for pro-Russian fighters who have not committed serious crimes, a corridor for fighters from Russia to leave the country, joint security patrols, early local and parliamentary elections and protections for the use of the Russian language.

Rebel leaders have dismissed the plan, and it remains to be seen to what extent they will comply.

Meanwhile, Ukrainian forces have restored control of the border with Russia and can now prevent military equipment from being taken across the frontier, the country’s acting Defense Minister Mykhailo Koval said Friday as a second successive day of fighting continued in the east.

"Our forces have completed the encirclement of the problem region and restored the state border of Ukraine. Last week we fully closed off the possibility of any military equipment being brought in from the Russian Federation," he said.

NATO Secretary-General Anders Fogh Rasmussen has accused Russia of deploying several thousand troops back to its border with Ukraine just weeks after withdrawing the majority of its forces and somewhat easing the threat of Russian military intervention.

Dismissing Rasmussen's remarks, Kremlin adviser Yuri Ushakov said, "There has been no buildup." He said Russia deployed more border guards because of security concerns, Reuters reported.

Friday's fighting took place about 75 miles from the border with Russia. Heavy weapons were seized from the separatists, including an armored personnel carrier, a truck with a high-caliber machine gun mounted on it, a shoulder-fired missile, grenade launchers and small arms, Seleznyov said in a Facebook post.

Fighting broke out east of the town of Krasny Liman early Thursday after pro-Russian separatists refused to lay down their weapons in line with Poroshenko's peace plan, government forces said.

Al Jazeera and wire services