Ukraine Speaker calls for keeping poisoning out of campaign

His comments followed a statement by Yushchenko himself that an investigation into the dioxin poisoning, which has disfigured his face, should proceed after the poll, which is being re-run after the Supreme Court declared the first attempt rigged.

Protests against election fraud brought much of Kiev to a halt for two weeks and raised the prospect of serious instability in the former Soviet republic.

Yushchenko returned to Kiev on Sunday after Austrian doctors concluded he had dioxin levels 1,000 times greater than normal. He has accused authorities of being behind the incident.

"We must not go into this over and over again until the election is over," said Speaker Volodymyr Lytvyn, who does not belong to the camp of either contender and played a major role in defusing tension caused by the tainted vote.