Toronto lawyer Selwyn Pieters announced on Twitter Monday that he is no longer representing Senator Don Meredith in his ethics case with the upper chamber as it reviews an internal report detailing the senator's relationship with a teenager.

Earlier this month the Senate's ethics watchdog found that Meredith, a Toronto-based senator, breached the Red Chamber's ethics code by engaging in an inappropriate sexual relationship with a young woman that started when she was 16 years old.

In an interview with CBC News Network's Power & Politics Pieters said the ethics officer looked at his client as a "predator" from the outset of her investigation because he is a black man.

"One has to consider the race factor here," he told host Rosemary Barton.​

In a series of posts Monday on Twitter, Pieters said that Meredith has retained alternative legal representation to "handle this very important and public interest matter."

That was one of the shortest and most hectic retainer I have ever taken on in my legal career. — feeling thankful —@selwynpieters

It remains unclear why Pieters is no longer representing Meredith, who is on sick leave from the Senate with no designated return date.

Meredith was appointed as a Conservative senator by former prime minister Stephen Harper in 2010 but now sits as an independent. He denied many of the allegations levelled against him by the woman in question — who is identified by Lyse Ricard, the ethics officer, as "Ms. M" in the report detailing the findings — but Meredith concedes that he had sexual intercourse with her on at least one occasion.

Several senators have urged Meredith to resign from the Senate and Rona Ambrose, interim leader of the Conservative Party, described his behaviour as "reprehensible" and said "of course he should resign."

Ricard's report has been referred to the Senate's ethics committee for review, which may recommend that the Senate as a whole take action — including a suspension.