Belarusians chanting “Step down!” filled the centre of the capital Minsk on Sunday in the biggest protest so far against what they said was the fraudulent re-election a week ago of longtime president Alexander Lukashenko, writes Reuters.

Russia said it would offer Lukashenko military help if necessary, but there was no visible police presence at the protest, which attracted around 200,000 people, a Reuters reporter estimated. At least two protesters have died and thousands have been detained in a crackdown since the vote.

The atmosphere at the rallies, which wrapped up late into the evening, was celebratory on the whole, with people carrying the red and white flags used in Belarus after the 1991 breakup of the Soviet Union before Lukashenko restored the Soviet version four years later.

Opponents of Lukashenko, in power for 26 years, say the vote was rigged to disguise the fact that he has lost public support. He denies losing, citing official results that gave him just over 80% of the vote.

The Kremlin said Russian President Vladimir Putin had told Lukashenko Moscow was ready to assist Belarus in accordance with a collective military pact if necessary and that external pressure was being applied to the country.