Who's sorry now? Not Tim Holding

Liberal deputy upper house leader Wendy Lovell has threatened to sue Mr Holding over mistaken claims he made about her alleged failure to declare Westpac shares properly.

Yesterday, Mr Holding repeated his comments that Ms Lovell had a "plausible" explanation, but he would not apologise or acknowledge he was wrong about her share holdings.

"We make no apologies at all for raising legitimate questions about the share holdings of members of the Liberal Party and their requirement to declare those interests," he said.

"If members provide plausible explanations as to their financial affairs, then that's fine."

Ms Lovell has never owned Westpac shares. Her mother owns the stock in question.

Ms Lovell said the minister's allegations were false and defamatory, and sought to discredit her integrity and honesty.

The row comes as Premier John Brumby criticised Opposition Leader Ted Baillieu for taking years to decide to put his multimillion-dollar share holdings into a blind trust.

"People have been calling for years and years and years for him to make that judgment," he said.

When questioned, Mr Baillieu would not explain the reason for last week's decision to put his stock into a blind trust.

"I'm not going to comment in any detail on that. The decision has been made, we've put it in place," he said.

At the time of the announcement, Mr Baillieu said the blind trust was to "ensure there can be no possible perception of any conflict of interest".