KIEV, Ukraine - Ukrainian authorities on Saturday attempted to appease anti-government protesters who have been demonstrating in the center of the capital for weeks by opening investigations against four top officials over the violent break-up of a small rally last month.

Opposition leaders dismissed the move as a half-measure and about 100,000 protesters turned out singing the national anthem in Kiev central square to demand that the president and the government resign.

A legendary Ukrainian rock band, Okean Elzy, performed in front of the jubilant crowd, dedicating the concert to all those who were detained and injured in the protests. "This is just the beginning," band frontman Svyatoslav Vakarchuk said.

The brutal police raid in the early hours of Nov. 30 galvanized the pro-Western protests sparked by President Viktor Yanukovych's decision to back away from signing a key integration treaty with the European Union, and instead turned toward Russia. Since that day's violence, protesters have also been demanding Yanukovych's ouster and early elections.