REPUBLICAN congressman Chris Collins, one of the first US politicians to declare support for Donald Trump’s presidential candidacy, was indicted by federal prosecutors on charges of securities fraud regarding an insider-trading scheme involving an Australian biotech company.

Mr Collins, 68, was arrested and charged along with his 25-year-old son, Cameron Collins, and the father of his son’s fiance, for their role in illegal trading of stock in Australian biotechnology firm Innate Immunotherapeutics, where the elder Collins was a board member.

Innate Immunotherapeutics was experimenting with a drug called MIS416 for treating multiple sclerosis.

Mr Trump is yet to comment on Mr Collins’ charge but has made it a pledge to “drain the swamp” of Washington corruption.

The indictment, released by the US lawyer for the Southern District of New York, accuses the congressman of tipping off his son about the results of Innate’s failed drug trial before the results were publicly released in June 2017.

Mr Collins broke the law by “passing material, nonpublic information regarding the drug trial results to his son … so that Cameron Collins could use that information to make timely trades in Innate stock and tip others,” the indictment alleges.

Cameron Collins is accused of passing on that information to his fiancee’s father, Stephen Zarsky, and others, who also benefited financially from the insider knowledge.

Prosecutors say his son sold nearly 1.4 million Innate shares.

Mr. Zarsky, 66, then sold all of his Innate shares and shared the tip with his brother, his sister and others before the public release of the trial results, according to the indictment.

The trades allowed the Collinses, Mr Zarsky and others “to avoid over $US768,000 in losses that they would have otherwise incurred” if they sold the stock after the announcement, according to the indictment.

On the day after the trial results were released, the company’s stock lost 92 per cent of its value.

Mr Collins reportedly said he has no plans to resign and will still run for re-election this year. He said any trial would clear both him and his son.

“We both look forward to clearing our good names and being exonerated at trial,” Collins wrote in the email, which was obtained by the Buffalo News. “Rest assured that I will continue to work hard for the people of the 27th Congressional District of New York while remaining on the ballot for re-election this November.”

Mr Collins has pleaded not guilty in Manhattan federal court.

Chris Collins’ lawyers responded swiftly, insisting he will be “completely vindicated.”

“We will answer the charges filed against Congressman Collins in court and will mount a vigorous defence to clear his good name,” they said in a statement.

Collins, who represents Buffalo’s suburbs and counties in upstate New York, was the first House Republican to openly support Mr Trump’s bid for the party’s nomination in the 2016 race, and he has remained a loyalist to the president.

House Speaker Paul Ryan said he’s removing the indicted congressman from the House Energy and Commerce Committee.

He’s also prodding his chamber’s ethics panel to pursue “a prompt and thorough investigation” of Mr Collins.

Mr Ryan issued his statement this morning calling insider trading “a clear violation of the public trust.”

He said he’s moving against Mr Collins even though a court will decide whether the politician is guilty of the allegations.

The House Ethics Committee said last August that it was investigating Mr Collins.