Ukrainian opposition lawmakers blocked the parliament rostrum on Tuesday, protesting authorities’ latest efforts to join NATO’S membership action plan. The lawmakers, led by former Prime Minister Victor Yanukovych, attached posters with the inscription “NATO will not pass!” to the presidium and rostrum, and demanded a referendum be held on the issue.

Meanwhile, members of the ruling faction led by Prime Minister Yulia Tymoshenko guarded the presidium to confront the opposition. Due to the confrontation between the two sides, Parliament Speaker Arseniy Yatsenyuk announced that Ukrainian President Viktor Yushchenko has decided not to deliver his scheduled addressto the parliament.

Yatsenyuk left the hall after the announcement and summoned leaders of all factions in parliament to seek a compromise to resume the legislature’s normal work.

However, analysts believed a quick solution is unlikely to be found.

Yanukovych said Monday the opposition demanded that a resolution be made stating the necessity to draft a law on Ukraine’s NATO entry.

He said Ukraine’s accession to NATO could take place only after a national referendum.

“Should such a resolution be issued, we will unblock the Supreme Rada (parliament),” he said.

In January, Ukrainian President Viktor Yushchenko, Prime Minister Yulia Tymoshenko and Parliament Speaker Arseniy Yatsenyuksent a letter to NATO Secretary General Jaap de Hoop Scheffer, expressing their hope that the country could join the NATO membership action plan at a NATO summit scheduled for early Aprilin Bucharest.

Yanukovych said any steps toward Ukraine’s NATO accession should be made after a referendum.

Ukraine’s leaders argued that participation in the NATO membership action plan does not automatically mean a country will be admitted to the bloc, therefore there’s no need for a referendum at this stage.

They assured a final decision on whether Ukraine should join the alliance would only be taken after a national referendum.