Czechs and Slovaks held solemn memorial services Thursday, commemorating the deadly 1968 Soviet-led invasion of Czechoslovakia, aimed at crushing the liberal reform movement known as the "Prague Spring."

Czech President Vaclav Klaus joined his Slovak counterpart, Ivan Gasparovic, at wreath-laying ceremonies in the Slovak capital, Bratislava, while prime ministers of both countries, Mirek Topolanek and Robert Fico came together in Prague.

The prime ministers laid one wreath at the tomb of Marie Charouskova, the 26-year-old student and mother shot dead by a Russian soldier on August 26, 1968 in Prague. Wreaths commemorating three other deaths were laid at Comenius University in Bratislava.

Historians say at least 100 civilians died in the two-month operation. And Thursday, Hungarian Culture Minister Istvan Hiller formally apologized on behalf of the Budapest government for Soviet-era Hungary's participation in the invasion.

Czechoslovakia split peacefully in 1993 into the Czech and Slovak republics.

In 2006, then-Russian President Vladimir Putin took moral, but not legal, responsibility for the invasion.

Some information for this report was provided by AP.