The number of seats now held by the grouping led by ex-premier Tymoshenko, who promised in August to form a radical opposition to arch rival Viktor Yanukovych's government, has now fallen to 126.
At the opening of Wednesday's parliamentary session, Oleksandr Moroz read the statements submitted by Maxim Lutskoy, Inessa Vershinina and Dmytro Kryuchkov announcing their decision to join the anti-crisis coalition, which comprises the Yanukovych's Party of Regions, the Socialists, the Communists and some members of the pro-presidential Our Ukraine bloc.
Tymoshenko, a charismatic leader of the 2004 "orange revolution" that swept Viktor Yushchenko to the presidency and saw her installed as his first prime minister, has repeatedly claimed that her political opponents in parliament have attempted to bribe members of her faction into changing the sides. She has failed to provide concrete evidence to support her allegations.
The Yulia Tymoshenko Bloc, which won 129 seats in the 450-member Supreme Rada during the March 26 elections, was the leading force in the first parliamentary coalition to emerge after the elections, but the alliance collapsed when the Socialists defected to join the Party of Regions.