Former Conservative cabinet minister Helena Guergis will never be readmitted to the Tory caucus, CBC News has learned. (CBC)

Former cabinet minister Helena Guergis, who was booted out of the Conservative caucus after Prime Minister Stephen Harper said he learned of "serious" allegations relating to her conduct, will never be readmitted, CBC News has learned.

A senior government source told CBC News that the matter "is behind us."

Guergis, the MP for the Ontario riding of Simcoe-Grey, now sits as an Independent. In April, Harper announced she had resigned from cabinet and that "pending a resolution, she will sit outside the Conservative party caucus."

Harper did not provide details about the allegations, but he said they were serious and he had immediately referred them to the Mounties, as well as to the commissioners for ethics and conflict of interest.

Although the probes into her alleged conduct have not been completed, the Tories have decided Guergis will never be allowed back in caucus.

The Conservative Party has already dropped Guergis as a future nominee in Simcoe-Grey. She is fighting this decision.

Guergis and her husband, former Edmonton Tory MP Rahim Jaffer, have been embroiled in a media storm that includes allegations of offshore financial accounts, illegal lobbying and conflicts of interest.

In an interview with CBC's Peter Mansbridge, Guergis said the Tories never told her the specifics of the "serious allegations" that prompted her dismissal. But the Conservatives have countered that Guergis was told the specific allegations by a party lawyer.

The Tories have also alleged that Jaffer used her office for business purposes, something Guergis denies.

She also has denied "absolutely false" allegations reported in the media that she and Jaffer participated in a dinner with Toronto businessman Nazim Gillani that involved escorts and cocaine.

She characterized allegations that the couple have offshore accounts as "laughable," and denied her husband ever illegally lobbied the government.