MANAMA, BAHRAIN, AND RIYADH, SAUDI ARABIA — Military troops and police moved against thousands of anti-government protesters occupying a landmark square in Bahrain's capital after the king declared a three-month state of emergency and instructed the military to battle unrest in the strategic nation.
Police and military units fired tear gas and began pushing into Pearl Square after daylight Wednesday. Shooting was heard, but there was no immediate word on casualties.
On Tuesday, at least two civilians and a soldier were reported killed when clashes erupted across the island nation. The king had imposed the state of emergency as sectarian strife deepened, inflaming tensions between the region's largest rivals, Iran and Saudi Arabia.
After the declaration of martial law by King Hamed ibn Isa Khalifa, Bahrain's armed forces said they were launching a "crackdown on lawbreakers," implying in a statement that they would move against the protesters, predominantly Shiite Muslims, who have occupied areas of the capital, Manama, and all but paralyzed the country.
A day earlier, Saudi Arabia sent forces to help quell the growing unrest.
It was unclear what specific role the Saudi troops and police units from the United Arab Emirates would play in the effort to quell the protests.
Bahraini television showed a second convoy of military vehicles entering the country late Monday, driving across the 16-mile causeway that links the two Sunni Muslim-ruled nations.
There were reports Tuesday that violence had flared outside the capital, in the predominantly Shiite Muslim area of Sitra and other suburban neighborhoods and villages. At least two deaths were reported in the clashes; as many as 200 were injured.
The Associated Press reported that a Saudi sergeant had been shot and killed by a protester in Sitra, according to Saudi security officials. The report could not be immediately confirmed.
The Saudi involvement, however, highlighted how a conflict that began over local grievances was evolving into a contest between Saudi Arabia and Shiite-run Iran for influence in Bahrain, which has a majority Shiite population. The growing regional tussling over Bahrain also has implications for the United States, which has a major military presence on the island, home to the U.S. Navy's 5th Fleet.
Iran stepped up its denunciation of Saudi Arabia's move to shore up Bahrain's monarchy.
"The presence of foreign forces and interference in Bahrain's internal affairs is unacceptable and will further complicate the issue," Foreign Ministry spokesman Ramin Mehmanparast said Tuesday at his weekly news conference in Tehran, according to news reports.
The Saudi presence was also denounced by some of Bahrain's Shiite opposition leaders, who described the presence of foreign troops as an "occupation."
Near Pearl roundabout in Manama on Tuesday, demonstrators who had occupied the traffic circle since last month were constructing more barricades blocking all major roads leading to the financial district. Several young men at the barriers had said they would try to block police or military units from entering the area.
"Certain locations will be evacuated and rallies disrupting the public order will be banned," a statement by the Bahrain Defense Force said. "Suspects will also be tracked down and arrested to face charges."
In other suburban neighborhoods populated largely by Sunnis, young men carrying sticks and metal rods, many with their faces covered, blocked roads and examined cars Tuesday.
"We are defending our homes from the Shia people," said one young man carrying a wooden club, who declined to give his name.
He and several associates had blocked a road in the suburb of Riffa, a mostly Sunni area that includes palaces used by the ruling family. An Interior Ministry policeman sat in his truck near the checkpoint, apparently unconcerned.
Iran and Saudi Arabia have long been rivals for a variety of religious and political reasons. Each country bases its legitimacy on Islamic law, but Iran subscribes to a rigid interpretation of Shiite Islam, and the Saudis follow a highly conservative form of Sunni Wahhabism.
"There's an ideological competition between the two countries to represent Islam," said Turki Hamad, a columnist for the Saudi newspaper Al Watan.
Iran has long made claims to Bahrain, while Saudi Arabia has seen the island as part of its sphere and has been a key patron of the royal family. The Saudis fear that the neighboring unrest may fuel protests among its own Shiite population, which is largely in the nation's oil-rich Eastern province next to Bahrain.
It remains unclear whether the Iranians have penetrated Bahrain's protest movement, which has tried to avoid a sectarian cast. Many protesters say they have no desire to see Bahrain come under Iranian influence.
But many Saudis are convinced that the campaign is guided by Iran, as Shiite movements in Bahrain and elsewhere in the region have been for 30 years, independent analysts said.
A military confrontation between Saudi Arabia and Iran over Bahrain is unlikely. But if clashes between Saudi troops and Bahraini protesters intensify, Iran could use proxies and other covert means to mount attacks in Bahrain, analysts said,
"If protesters target Saudi soldiers or march on the Saudi Embassy and if the Iranians start escalating their response, you could have another Lebanon," said Rachel Bronson at the Chicago Council on Global Affairs.
Times wire services contributed to this report.