Some 100,000 workers on Thursday paraded on Red Square for the first time since the 1991 Soviet breakup as the takeover of Crimea triggered a surge of patriotism and boosted Russian President Vladimir Putin's standing.
A huge column of demonstrators waving Russian flags and balloons marched through Moscow's iconic square near the Kremlin walls as trade union leaders addressed them from the podium on International Labour Day.
"Putin is right", "Proud of the country" and "Let's support decisions of our president" read the banners carried by the smiling demonstrators, a colourful spectacle harking back to Soviet times.
Moscow police said more than 100,000 people took part in the "march of trade unions" on Red Square.
Since returning to the Kremlin for a third term in 2012 after huge protests against his decade-long rule, Putin has sought to boost support among his core constituents of middle-aged Russians and blue-collar workers.
After Moscow's takeover of Ukraine's Crimean peninsula in March, patriotism in Russia has surged to new heights and lifted the 61-year-old president's approval ratings.
A new study by the independent Levada Centre pollster released on Wednesday said that 82 percent of respondents said they approved of Putin's job.
Some two million people turned up for May Day demonstrations across Russia, trade union leaders said.
Over the past years, Putin has cleverly tapped into middle-aged Russians' nostalgia for the stability and super-power status of the USSR and even revived Soviet-era awards.
Later Thursday, Putin is expected to bestow "Hero of Labour" medals on several Russians.
International Labour Day, or May Day, was a key date in the Soviet calendar, instituted after the Bolshevik Revolution.
The celebrations became increasingly elaborate in the later years of the USSR, with party bosses presiding over ranks of marching athletes, soldiers, farm labourers and factory workers from the Lenin Mausoleum on Red Square, awash with red flags.