Rebel activists in eastern Ukraine have released seven Red Cross workers they had detained late Friday. The workers were released in Donetsk Saturday. A Red Cross official told the Reuters news agency that one of the workers had been badly beaten.
The pro-Russian separatists had indicated earlier they believed the Red Cross team was engaged in espionage.
On Friday, Ukrainian troops driving armored vehicles in the port city of Mariupol smashed through barricades surrounding a police station occupied by pro-Russian separatists. Witnesses say the attack killed at least seven people, and television footage showed the building reduced to smoldering rubble.
The new violence in the southeastern port city on the Azov Sea came ahead of Sunday's vote in the region to decide whether to secede from Ukraine and establish an independent Donetsk People's Republic. A similar referendum is set for the nearby Luhansk region.
The government offensive also came as Russian President Vladimir Putin visited Ukraine's Crimea peninsula for the first time since Moscow annexed the territory in March. Mr. Putin told military personnel in Sevastopol Friday that 2014 would be remembered as "the year when the people living here firmly determined to be together with Russia."
The United States, which does not recognize the annexation, called the Russian president's visit "provocative and unnecessary," and the annexation "illegal and illegitimate." Ukraine's Foreign Ministry denounced the visit as a "flagrant violation" of the country's sovereignty and a "provocation."
The Ukraine offensive in Mariupol, a city of 465,000 residents, marks the second time this week that government security forces have engaged the armed separatists.
A video posted to the Internet Friday purports to show anti-Kyiv demonstrators, apparently unarmed, being shot in the streets of Mariupol as tanks drive by (https://www.youtube.com/watch?v=kno4MEp9sPY). Another video purports to show a member of Ukrainian security forces being shot, apparently by a sniper, after which some of the anti-government civilians at the scene applaud https://www.youtube.com/watch?v=nLN9rfJySRE).
The content of the videos could not be independently confirmed.
On Thursday, Russian media quoted separatist leader Denis Pushilin as saying Sunday's secession referendum will ask residents to vote yes or no on whether they support a "proclamation of state independence." Luhansk residents will be asked the same question.
Recent polling indicated 70 percent of residents in eastern Ukraine want to remain in the country.
