Clashes between demonstrators and pro-government loyalists left hundreds injured in Bahrain on Friday, the Wall Street Journal reported.

The clashes come just two days after Bahrain lifted its emergency laws and marks the worst outbreak of violence in the tiny island kingdom since the military was ordered off the streets nearly three weeks ago.

Eyewitnesses on the outskirts of Bahrain's capital, Manama, told the WSJ police fired tear gas and rubber bullets to disperse tens of thousands of anti-government protesters, mainly Shiites, who were attempting to march on the royal complex of Riffa. They were confronted by pro-government loyalists who, armed with swords, sticks and clubs, had gathered to protect the predominantly Sunni neighborhood.

Bahrain's Ministry of Interior denied rubber bullets had been used.

"Rumors that live ammunition or rubber bullets were used, causing many injuries, or that people had inhaled gas to the point of suffocation are totally without foundation. This is supported by video footage of the operation," the ministry said in a statement.

Before the violence erupted police cordoned off the area to keep the anti-regime marchers from getting close to the offices of the Sunni ruling family. The attempt by police to disperse the crowds then sparked violent confrontations.

Eye witnesses said police formed a line between the two groups in the hope of averting violence – but did not succeed.

Two doctors at the A'aili Health Center where most of the injured anti-government protesters were taken said the bulk of injuries were fractures inflicted by clubs and sticks and suffocation from tear gas.

A third doctor estimated that about 300 people had been injured but that there had been no deaths.

"We are seeing mainly fractures and chest injuries from the [tear] gas. I've seen injuries to the chest, abdomen, neck and head, all from rubber bullets," Ali Alekri, an orthopedic surgeon who came to the center to help from Manama's main Salmaniya hospital, told WSJ.

The government cast doubt on the veracity of such reports, saying they came from opponents of the regime.

Friday's clashes marked the first major violence since Crown Prince Salman bin Hamad al-Khalifa ordered the military off the streets nearly three weeks ago and called for talks with the mainly Shiite opposition.

Preceded US Diplomatic Visit

The violence came hours before U.S. Defense Secretary Robert Gates paid a surprise visit Friday to Bahrain in a show of support for the island kingdom's royal family. Bahrain, which holds a strategic position in the Persian Gulf, hosts the headquarters of the U.S. Fifth Fleet—a home to 3,000 military personnel who oversee 30 naval ships and some 30,000 sailors.

Bahrain's ruling Sunni minority comprises around 30% of Bahrain's 1.2 million population and fear the nation's Shiite majority have been co-opted by Shiite powerhouse Iran across the gulf in its ambitions of creating an Islamic super-state.

Gates's visit–intended as a show of support for Bahrain's king – was instantly complicated by Friday's violence. The defense secretary had been expected to take on an unusual diplomatic role, delivering a message of support to the ruling family, while encouraging leaders to engage in dialogue with the opposition.

"Bahrain is a front-line state in a regional competition with Iran," said a senior defense official. "It's a very, very important strategic partner."