Ukraine's Privatbank has temporarily closed its branches in the Pro-Russian regions of Donetsk and Luhansk, citing criminal activities that could "threaten the lives" of its workers.

"In the current circumstances we cannot and do not have the right to make people go to work in the Donetsk and Luhansk regions, where armed people break into bank branches and seize security vans in the towns," the largest commercial bank in the country said in a statement.

"Over the last 10 days, 38 ATMs, 24 branches of Privatbank and 11 cash collection vans have suffered arson, assault and wanton destruction in the cities of Donetsk and Luhansk."

Nevertheless, the bank's clients in the regions will be able to access their accounts via the internet and mobile devices, use their cards in shops and make cashless transactions. Privatbank has more than 400,000 pensions and other social benefits for 220,000 people in both regions.

Pro-Russian separatists have been targeting the bank after its co-owner and Ukraine's fourth-richest man, Igor Kolomoisky, announced that he would give $10,000 (£5,900, €7,200) to Ukrainian troops for every Russian "saboteur" handed over. He also announced rewards for arms seized from them.

They set fire to a branch in the town of Mariupol in the Donetsk region late on 3 May and raided a security truck last week in Horlivka.

Kolomoisky was earlier appointed by the new government of Ukraine as the leader of the regional militia in Dnipropetrovsk, which borders Donetsk.

Back in March, he pledged a $25m donation to help kick-start the Ukrainian military in eastern Ukraine, though it is not clear how much he actually spent. The Guardian reported that he spent "several million dollars" to buy car batteries and fuel for the Ukrainian military.