The EU has added Belarusian leader Alexander Lukashenko and his son Viktor to its sanctions blacklist of Belarus officials, bringing the total to 59.
The 15 added on Friday also include KGB secret police chief Ivan Tertel and President Lukashenko's chief of staff Igor Sergeenko.
The EU rejects Mr Lukashenko's claim to have won re-election on 9 August and deplores his crackdown on opponents.
His son Viktor, 44, is a national security adviser.
Protests have swept the country since its long-time leader said he had won the vote, which was widely viewed as rigged.
The main opposition leader, Svetlana Tikhanovskaya, said she had attracted between 60 to 70% of the vote and was forced into exile in neighbouring Lithuania immediately after the election.
The election-monitoring organisation, OSCE, said on Thursday that human rights abuses since the vote "were found to be massive and systematic and proven beyond doubt", and called for the official result handing Mr Lukashenko victory to be annulled "due to irregularities at all stages of the process".
UK Foreign Secretary Dominic Raab said the OSCE report had "exposed the fraud at the heart of the presidential elections" and he called for "new elections which are free and fair".