Alberta MLA Mike Allen has resigned from the Progressive Conservative caucus after he was arrested Monday in St. Paul, Minn., in a prostitution sting.

"Today, I informed the Chief Government Whip of a legal incident that I have been involved in," Allen, the MLA for Fort McMurray-Wood Buffalo, said in a written statement.

"Pending resolution of this incident, I have resigned from the government caucus and all legislative committees effective immediately."

Government whip Steve Young said in a news release that he accepted Allen's resignation. The office of Premier Alison Redford said it will not be commenting.

In his statement, Allen apologized to his family, friends, constituents, colleagues and Albertans for "the embarrassment I caused."

"It is a mistake for which there are no excuses and for which I accept full responsibility," Allen said. "This is a deeply embarrassing moment and all I can say is that I am sorry and I humbly ask for forgiveness.

"I will work long and hard to regain the trust of the many I have let down."

Undercover police officers posted ad

According to St. Paul Police, undercover officers posted an ad for escort services on a local classified advertisement site called "Backpage." Police allege that Allen answered the ad.

"He did meet with two vice personnel from our police department and made arrangements for a service," said Sgt. Paul Paulos, a spokesman with the St. Paul Police Department.

Allen was in St. Paul to attend the Council of State Governments Midwestern Legislative Conference.

Calgary MLA Wayne Cao, the only other Alberta politican with Allen on the trip, said the two didn't see much of each other during the conference.

He said he was surprised when he heard Tuesday afternoon that his fellow Tory had been arrested.

"The news hit me," he said. "Shocked, surprised in a way. But then I look around the conference going on and I see the items that I have to cover. So life goes on."

Cao said the two didn't see much of each other during the conference as they were splitting duties.

Cao, who is staying in Minnesota Wednesday for the final day of the conference, said he is embarrassed by the arrest.

"If somebody says, ‘Oh, your colleague’s from Alberta,' I feel embarrassed, Cao said. "Just like any other Canadian, we carry along with pride of our province, and our country, Canada. And something happens. I’m very unhappy about that."

Allen released from custody

Allen, who was arrested but not formally charged, has been released from custody.

In Minnesota, accused are issued a citation which allows police to bring them to jail, take fingerprints and take a booking photograph.

Police will write a probable cause statement in the case which will be reviewed by the St. Paul city attorney's office.

If there is enough evidence, then the charges are moved forward, allowing a court date to be set and a summons issued.

While Allen stepped down from the government caucus, he still remains the MLA for Fort McMurray-Wood Buffalo, which prompted Wildrose leader Danielle Smith to call for him to resign his seat.

"Albertans expect their elected officials to follow a higher ethical standard of behaviour and to obey the law, both of which Mr. Allen failed to do," Smith said in a news release.

"For an MLA to behave in this manner while travelling abroad on government business is unacceptable and he owes it to the people of Fort McMurray and all Albertans to immediately resign."

Allen is a former member of the Wood Buffalo Regional Municipality which includes the city of Fort McMurray.

He was first elected as a PC MLA in April 2012. Shortly afterwards, Redford appointed him a special advisor to the transportation minister on the twinning of Highway 63.