Security forces and protesters clashed in Bahrain on Sunday during the most violent day in weeks, and hundreds marched in Saudi Arabia to demand the release of prisoners who have been detained without charges.

Witnesses in Bahrain said that more than 100 people were injured after police fired tear gas at protesters and attacked them with batons. The demonstrators were trying to shut down the financial center of Manama, Bahrain’s capital, on the first day of the country’s workweek. Protesters threw gas canisters and stones at police.

In Yemen, police on rooftops fired live bullets and tear gas at protesters, also injuring more than 100 people, a day after security forces killed seven demonstrators in protests around the country.

The White House issued a statement strongly condemning the violence in both Yemen and Bahrain.

“We urge the governments of these countries to show restraint, and to respect the universal rights of their people,’’ the statement said. It called in particular on the government of Bahrain “to pursue a peaceful and meaningful dialogue with the opposition rather than resorting to the use of force.’’

In Riyadh, the Saudi capital, hundreds of family members of people who have been jailed without charges rallied in front of the Interior Ministry calling for their release, said Mohammed al-Qahtani, founder of the Association of Civil and Political Rights in Saudi Arabia. The protest was peaceful, with no clashes between police and demonstrators, he said.

In Bahrain, witnesses said that protesters had begun the day by blocking a main highway used for access to the financial district in Manama. Police attempted to clear them away with tear gas and rubber bullets.

Clashes later took place between pro-government supporters and protesters near the University of Bahrain, witnesses said, and police broke up those fights with tear gas.

By day’s end, Crown Prince Salman bin Hamad al-Khalifa announced that he had agreed to discuss electoral reforms that could potentially satisfy at least some of the protesters’ demands. He said he would talk with opposition political groups about “a government that represents the will of the people.’’

The clash followed one that took place Friday near a royal palace, where protesters were met by government loyalists armed with sticks and swords.

Protesters have been in the streets for weeks, calling for democratic reforms and an end to what they say is systematic discrimination against the country’s Shia majority by the Sunni royal family.

Seven protesters were killed by security forces in the first week of the protests, but until Friday the situation had remained relatively peaceful since the initial deaths.

On Sunday, the Interior Ministry said that a police officer had been stabbed and another suffered a head injury in a clash with a group of protesters. In a statement, the ministry told protesters to return to Pearl Square, which has been the hub of
the month-long demonstrations, “for their own safety.”

The clash in Yemen involved demonstrators who had been camping on the grounds of
Sanaa University, the latest in weeks of demonstrations calling for the Yemeni president to step down.

In addition to firing tear gas and live ammunition, police and government supporters wielding clubs and knives also attacked protesters on the ground, Mohammed al-Abahi, a doctor in charge of a makeshift hospital near the university, told the Associated Press.

Among the injured, more than 20 suffered gas inhalation, and one was in critical condition after being shot, the doctor said, according to the AP report.

In Saudi Arabia, the march in Riyadh by protesters calling for the release of prisoners came after no one turned out in the capital for planned “Day of Rage” demonstrations across the country.

Hundreds protested in the country’s Eastern Province on Friday, but a strong police presence in Riyadh discouraged demonstrators from turning out there, witnesses said.

Oman’s Sultan Qaboos bin Said, in an apparent attempt to quell protests that have shaken that country since last month, announced that he would increase welfare and pension benefits and grant some legislative and oversight powers to a partially elected council, according to the state news agency. The council currently serves in an advisory role.