Paul Martin has formally transfered control of Canada Steamship Lines to his sons, keeping a promise he made to earlier this year to MPs who raised concerns over potential conflicts of interest.

"As of August 25, 2003 I no longer have any interest in or control over CSL whatsoever," Martin said in a statement Wednesday.

"As I said in March, my three sons have always owned the company. They now control it fully as well."

But the move failed to silence critics who say that, as long as CSL remains in the family, the man expected to become Canada's next prime minister hasn't solved his problem.

"As prime minister Mr. Martin will have a responsibility to all Canadians, not to the special interests of his children," Canadian Alliance MP Deborah Grey told reporters.

"There are still many questions that remain unanswered."

Martin told a news conference later in the day he will refrain from dealing with shipping related issues, even though federal Ethics Counsellor Howard Wilson said he doesn't need to do that.

Wilson said in July that there will be some specific areas "rare and easily managed" where Martin, as prime minister, will have to avoid cabinet discussions.

He said the business "does not raise significant conflict of interest issues if you were to become Prime Minister, no more than they did when you were Finance Minister for eight years."

Martin's statement on Wednesday said CSL will continue to disclose its activities to the Ethics Counsellor. As well, a code of Corporate Social Responsibility has been established.

The favourite to replace Jean Chretien came under fire earlier this year when opposition parties suggested Martin might find himself in conflict with the shipping company's corporate interests if he becomes prime minister.

Martin agreed in March to transfer control of the company to his three sons, Paul, David and James.

Grey said Martin is setting "himself up for future conflicts of interest" by keeping the company in family hands.

An aide told The Canadian Press that Martin will receive no personal financial benefit under the transfer. However, his wife Sheila will benefit from $829,000 in shares in a family holding company that will be held in trust to provide future financial security for her.

Martin's wife has signed a waiver saying she will not be entitled to any management information about the holdings, and no dividends will be paid during her husband's lifetime.

No dividends will be paid on the shares during her husband's lifetime and the ultimate value of her shares will remain fixed. That is a precaution to guard against any suggestion she and her husband might benefit from the result of CSL's future corporate performance.

But Martin is hanging on to at least one indirect stake in CSL -- the pension he receives from the company. When asked, Martin refused to say how much it is worth.

"That's a personal matter," he said. "But the one thing that I can make very clear to you is that, in fact, my pension has nothing to do with the company's earnings or the company's growth."

Martin bought CSL with a partner in 1981 for a reported $180 million. He later bought out the partner.

Since CSL is privately held there are no public stock quotations, but estimates of the firm's current value range upwards of $400 million.

With a report from The Canadian Press