Thousands of supporters of ex-president Mohamed Nasheed, who says he was forced to resign last month under threat of violence, surrounded the People's Majlis, while legislators from his Maldivian Democratic Party (MDP) stopped proceedings inside.
New President Mohamed Waheed Hassan Manik, who was due to address the opening session, was unable to enter despite the presence of scores of riot police and soldiers.
Nasheed, the islands' first democratically elected president, and his party say he was ousted in a bloodless coup on February 7 and that Waheed's government is illegitimate.
They have vowed peaceful street protests until early elections are called. Polls are due in October 2013.
Police spokesman Ahmed Shiyam said 44 people had been arrested, and fourteen officers were injured in skirmishes. Many protesters sat on the street outside parliament, wearing goggles and surgical masks in anticipation of being tear-gassed.
The United States criticised the "disorderly protests", and urged dialogue to create the conditions for an early poll.
"The United States encourages all parties to continue to work collaboratively and peacefully toward a solution ... and not allow violence to further complicate the situation," the U.S. Embassy for Sri Lanka and the Maldives said in a statement.
The 54-nation Commonwealth said it had appointed its former secretary-general Donald McKinnon as special envoy to the Maldives. Along with India, the Commonwealth has been at the forefront of diplomatic efforts to end the standoff.
The Commonwealth last month suspended the Maldives from its democracy watchdog group and it has backed early elections to end any question over the legality of the transfer of power.
Images sent out on Twitter by MDP legislators from the parliament chamber showed them sitting on the speaker's desk, while others blocked Speaker Abdulla Shahid from entering.
Later, soldiers forcibly removed two MDP legislators. That is not without precedent in the rambunctious parliament, which saw a quarter of its sessions canceled because of disruptions and is ranked among the archipelago nation's most corrupt institutions.
Copyright Thomson Reuters