The United States is considering targeted sanctions against Syrian officials to respond to "completely deplorable" violence used by Damascus's forces to crush dissent, an official said Monday.

Signs of a more muscular U.S. response to violence in Syria followed an assault by Syrian troops backed by tanks in the flashpoint town of Daraa, which killed at least 25 people, as a building crackdown reached new heights.

Syrian troops backed by tanks stormed the flashpoint town of Daraa on Monday killing at least 25 people, witnesses said, as a leading rights activist accused Damascus of opting for a "military solution" to crush dissent.

Troops also launched assaults on the towns of Douma and al-Muadamiyah near Damascus, witnesses said, as the head of the U.N. human rights agency slammed what she said was the Syrian security forces' disregard for human life.

Syria on Monday sealed off its border with Jordan, the kingdom's information minister Taher Adwan said, hours after troops backed by tanks swept into the Syrian southern flashpoint town Daraa.

"Syria closed its land borders with Jordan. The Syrian decision is related to the internal situation in Syria," Adwan told the state-run Petra news agency.

Yemeni security forces wounded dozens of people as they fired bullets and tear gas to disperse hundreds of thousands of protesters in the flashpoint city of Taez on Monday, witnesses said.

Large crowds gathered in Taez, south of Sanaa, to pressure President Ali Abdullah Saleh to step down immediately despite a U.S.-backed Gulf plan for a transition, they said.

The U.S. government is preparing sanctions against senior officials in the entourage of Syrian President Bashar Assad who are overseeing a violent crackdown against protesters in the country, The Wall Street Journal reported late Sunday.

Citing unnamed officials, the newspaper said the administration of Barack Obama was drafting an executive order empowering the U.S. president to freeze the assets of these officials and ban them from any business dealings in the United States.

A roadside bomb explosion wounded four people, including two policemen, near a small church in the Iraqi capital on Easter Sunday, medical and security officials said.

The bomb went off near the entrance of the Sacred Heart church, which is surrounded by concrete blast walls, near Tahriart Square in central Baghdad.

Yemen's protest movement on Sunday insisted on the quick exit of President Ali Abdullah Saleh after his ruling party accepted a Gulf plan for him to quit in 30 days in a move hailed by Washington.

The United States had urged a peaceful transition after Saleh's General People's Congress (GPC) party said late Saturday it accepted a Gulf Cooperation Council (GCC) plan under which he would quit following months of protests.

Security forces raided homes across Syria, arresting regime opponents, as funerals were held on Sunday for protesters and mourners killed in a bloody crackdown which activists said cost 120 lives.

Despite a relative lull, security forces killed three more people in the Mediterranean town of Jableh, near the port city of Latakia, Facebook page The Syrian Revolution 2011, a driving force behind the protests, reported.

Clashes between south Sudan's army and rebel militiamen killed at least 55 people, a government official said Sunday in the soon to be independent state gripped by a bloody wave of unrest.

The fighting raged for about three hours on Saturday in Jonglei state between the southern Sudan People's Liberation Army (SPLA) and gunmen led by former militia leader Gabriel Tang, also known as Tang-Ginye.

Yemen's embattled president agreed Saturday to a proposal by Gulf Arab mediators to step down within 30 days and hand power to his deputy in exchange for immunity from prosecution, a major about-face for the autocratic leader who has ruled for 32 years.

A coalition of seven opposition parties said they also accepted the deal but with reservations. Even if the differences are overcome, those parties do not speak for all of the hundreds of thousands of protesters seeking President Ali Abdullah Saleh's ouster, and signs were already emerging that a deal on those terms would not end confrontations in the streets.