Ukraine's government has raised almost $8 million in cryptocurrencies after posting appeals on social media for donations of bitcoin and other digital tokens, according to blockchain analysis company Elliptic.

Ukraine's official Twitter account made the appeal for cryptocurrency donations on Saturday following the country's invasion by Russia, posting digital wallets addresses for tokens including bitcoin BTC=BTSP and ether ETH=BTSP.

Ukraine's Vice-Prime Minister Mykhailo Fedorov Tweeted the wallet addresses. "Stand with the people of Ukraine. Now accepting cryptocurrency donations," wrote Fedorov, who is also minister of digital transformation.

The donations came as Russian military vehicles pushed into Ukraine's second-largest city Kharkiv on Sunday and explosions rocked oil and gas installations on a fourth day of fighting in the biggest assault on a European state since World War Two.

By 1030 GMT Sunday, the wallet addresses had received crypto worth $7.9 million across almost 11,500 donations, London-based Elliptic said. The company tracks the movement of digital coins on the blockchain, a public ledger that records crypto transactions.

Ukraine's ministry of digital transformation did not immediately reply to requests for comment.

Its crypto crowdfunding appeal is unprecedented. Though some states such as El Salvador have embraced cryptocurrencies, Ukraine's appeal for direct donations is among the first of its kind. It was not clear what Kyiv would use the funds for.

Crypto donations to Ukrainian volunteer and hacking groups have also spiked since Russia launched its invasion on Thursday, Elliptic said this week.

The donations to such groups, some of which have supplied equipment to government forces, grew strongly in January as Russia massed troops near Ukraine's border ahead of its invasion.