By Warda Al Jawahiry and Frederik Richter
MANAMA (Reuters) - Bahraini riot police fired thick clouds of tear gas and pushed back protesters who blocked a main thoroughfare leading to the Bahrain Financial Harbour, a key business district in the Gulf Arab region's banking center.
Forming a thick line across the motorway, police fired dozens of tear gas canisters at protesters and pushed them back toward Pearl roundabout, the focal point of weeks of demonstrations on the small Gulf island.
Police appeared to outnumber protesters early on, but hundreds of people rushed to the area as news spread.
A Western banker who declined to give his name said the protesters had stopped him from entering the Financial Harbour: "They didn't let me through and they were very aggressive. This is not peaceful any more. It's time for police to stop this."
Bahrain has been gripped by its worst unrest since the 1990s after protesters took to the streets last month, inspired by uprisings that toppled the leaders in Egypt and Tunisia.
The kingdom, home to the U.S. Navy's Fifth Fleet, has seen weeks of rallies by its disgruntled Shi'ite Muslim majority, which says it is discriminated against by the Sunni al-Khalifa ruling family.
An opposition activist who is part of a bloc of six moderate groups said the Financial Harbour protest was a step too far.
"It was a mistake to go to the Financial Harbour. There is enough room in the square for protests," he said, declining to give his name. "It was a small group and it's not popular, the consensus was on the square."
Thousands of the nascent February 14 youth movement still occupy Manama's Pearl roundabout, and have organized daily protests.
The opposition appears increasingly split, however, between the mainstream, which wants peaceful rallies calling for a new government and constitutional reform, and smaller groups intent on bringing down the royal family with more provocative action.
The youth movement said late on Saturday that it would form a human chain to block entry to the Financial Harbour from noon on Sunday, the first day of the working week in Bahrain. Several protesters set up camp in the area on Saturday night, however, and were blocking traffic early in the morning.
Police also advanced on the protesters from the other side of the motorway, apparently trying to hem them into the Pearl roundabout and prevent them from causing disturbances elsewhere.
Helicopters circled overhead and ambulances headed to the scene. Several people were taken away after inhaling tear gas.
Some Shi'ite opposition groups sent out messages calling on people to come to the roundabout to face off against police.
"I'm annoyed with the government that they've let this build so far. With civil disobedience, the protesters have a really nice tool at their hands. But the government should keep the roads open," said a Western banker, walking off to try to reach his car as tear gas battles continued just 50 meters away.
(Additional reporting and writing by Lin Noueihed; Editing by Crispian Balmer)