Top European Union officials have written to Poland's right-wing government seeking "reassurance" it will obey a ban on logging in Europe's last primeval woodland, sources said on Monday. Brussels has also pushed the bloc's top court to act urgently on the fate of the Bialowieza forest after the ruling Law and Justice party vowed that it would continue to log in the UNESCO world heritage site. "First Vice-President Frans Timmermans and the Commissioner for Environment Karmenu Vella sent a letter to the Polish authorities on Friday 4 August asking for reassurance that Poland will fully respect the interim measures issued by the Court of Justice concerning the Bialowieza forest," a Commission source told AFP.