Key legislative changes required for Ukraine's bid to join the World Trade Organisation were stalled Wednesday during a rowdy parliament session marked by fistfights and the wail of sirens.

By late afternoon, the chamber had passed only three out of 14 government-sponsored bills, which have to be enacted in order to advance Ukraine's bid to join the 148-member WTO.

The government has been pushing to have the legislation adopted before parliament adjourns for its summer recess on July 8. Among the bills that did get through Wednesday was a measure that criminalises the distribution of pirated compact discs and equipment for their manufacture.

Passage of that law should boost Ukraine's chances of signing a bilateral agreement with the United States, as Washington has pushed Kiev to enact the measure.

Another bill simplifies procedures for foreign nationals to receive audit licenses, and a third eases imports and ups safety requirements for trucks and buses.

Bedlam reigned for much of Wednesday's session, with several fights breaking out as opposition deputies tried to block passage and discussion of the bills.