The RCMP is investigating a security breach on Parliament Hill, allegedly by Pierre Poilievre, the parliamentary secretary to the prime minister.

The investigation focuses on an incident Tuesday morning, when the 30-year-old Tory MP arrived on Parliament Hill to park his car.

Poilievre was reportedly waiting behind a delivery truck to clear the security gate. He appeared to grow impatient and pressed the security gate to let himself through, sparking an argument with RCMP officers.

Everyone entering Parliament Hill must pass through security, including elected officials.

The Ottawa-area MP has since apologized for the incident, and said he won't use the same entrance again.

"I should've waited a little bit longer," he told CTV News. "I accepted responsibility. I've told security folks here. I apologized to them."

Poilievre added that in his opinion, the matter has been resolved. But the incident has prompted attacks by at least one member of the Opposition.

"It's inappropriate for an MP to jump out of his car, push the RCMP button and go through without proper clearance," said New Democrat MP Pat Martin. "He should be hanging his head in shame."

Security expert Doug Kirkland told CTV the breach is cause for concern.

"Parliament is his working home. So if he can't respect the rules in his own home -- what does that say?"

With a report from CTV parliamentary correspondent Richard Madan