Syrian companies linked to President Bashar al-Assad's regime may be next to be hit by European Union sanctions, diplomatic sources said Wednesday.

"There is talk of strengthening sanctions against Syria with new measures, but there is no text as yet on the table," a European diplomat who asked not to be identified told Agence France Presse.

Syrian dissidents warned Tuesday of a harsh backlash as troop reinforcements headed to northwestern Syrian after the authorities said 120 policemen were massacred in the town of Jisr Shughour.

The Syrian Revolution 2011, a Facebook group spurring protests against Syrian President Bashar al-Assad, called for "Tuesday of resurrection" rallies and appealed to the army to protect civilians against regime agents.

Syrian opposition activists in Europe urged the international community Sunday to increase pressure on President Bashar al-Assad and called for an independent investigation into his regime's deadly crackdown.

The roughly 200 activists gathered in Brussels also said charges should be laid against those responsible for violations of human rights in the repression, and cases brought before the International Criminal Court.

Thirty-eight people, including six members of the Syrian security forces, were killed in 24 hours during clashes in the northwest town of Jisr Shughour, a Syrian rights activist said on Sunday.

"Thirty-eight people were killed in shootings in the region of Jisr Shughour, 10 yesterday and 28 today," Rami Abdul Rahman, head of the London-based Syrian Observatory for Human Rights, told Agence France Presse.

Israeli gunfire killed 22 people and wounded about 350 others on Sunday as demonstrators on the Syrian side tried to cross the ceasefire line on the annexed Golan Heights, Syria's state-run SANA news agency reported.

"The protesters, hundreds strong, were both Syrian and Palestinian," SANA said.

U.S. Secretary of State Hillary Clinton said Thursday that the international community needs to be more united on dealing with the Syrian government's crackdown on the pro-democracy movement there.

"Right now the attitude of the international community is not as united as we are seeking to make it," the chief U.S. diplomat told reporters.

Britain believes that Syria should be reported to the U.N. Security Council over its alleged illicit nuclear activity, Britain's ambassador to the International Atomic Energy Agency (IAEA) said Wednesday.

In a restricted report circulated to member states last week, the U.N. watchdog said it was "very likely" that a remote desert site in Syria bombed by Israeli planes in 2007 was indeed a covert nuclear reactor, as alleged by the United States.

China voiced support on Tuesday for Syria's stability and said a U.N. Security Council resolution on the nation was unlikely to ease tensions there.

Syrian Deputy Foreign Minister Faisal al-Mekdad is currently in Beijing and is slated to hold talks with Chinese Foreign Ministry Yang Jiechi, ministry spokeswoman Jiang Yu told journalists.

At least 15 people were killed in a Syrian crackdown on pro-democracy protesters, activists said Monday, as the U.N. condemned the "shocking" brutality of President Bashar al-Assad's regime.

Dozens of tanks for a second straight day circled towns and villages in the Homs area, north of Damascus.

Syrian security forces killed at least eight people on Friday as anti-regime protests broke out across Syria, including in the capital Damascus, activists said.

"We have three people killed in the southern town of Dael, three others in the Damascus suburb of Qatana, one in the suburb of Zabadani and another in Jableh, located near the coastal city of Latakia," said Rami Abdul Rahman, head of the London-based Syrian Observatory for Human Rights.