U.S. Secretary of State Hillary Clinton met with Norwegian officials Friday as she toured Scandinavia to praise the work of key U.S. partners in a range of global hotspots.

Syrian regime forces opened fire on protesters in the Douma area near the capital on Friday, as at least 43 people were killed in violence across the country, a rights group and activists said.

Regime forces killed 13 people in the countryside around Damascus, eight in the central province of Homs, nine in the northern city of Aleppo and its countryside, three in the central province of Hama, three in the northwestern province of Idlib, two in the coastal province of Latakia, two in the Damascus neighborhood of al-Mazzeh, two in the eastern province of Deir Ezzor and one in the southern province of Daraa, the Local Coordination Committees, the main activist group spurring protests on the ground, reported.

Germany on Friday urged Russia to curb its support for Damascus, ahead of President Vladimir Putin's visit to Berlin and Paris that is set to be dominated by the escalating Syria crisis.

"In our view Russia should recognize that we are not working against Russian strategic interests when we want to stop the violence in Syria," Foreign Minister Guido Westerwelle told Die Welt ahead of Putin's arrival.

U.S. Defense Secretary Leon Panetta said Thursday that any military action in Syria would need backing from the United Nations, but called recent violence "intolerable."

Asked if he could foresee a scenario in which the United States would back military intervention even without U.N. authorization, Panetta said: "No, I cannot envision that."

Russia has worked "constructively" on the Syria crisis at the U.N. Security Council, German Chancellor Angela Merkel said Thursday, a day before she hosts talks with the Russian president.

"Russia has cooperated constructively in the U.N. Security Council," Merkel told a press conference in the German town of Stralsund at the end of a Baltic Sea summit of heads of government from 11 countries.

Syria-based insurgents fighting the regime of President Bashar Assad on Thursday took to task their exiled leadership, in a stark show of divisions within the armed opposition.

"Nobody has the right to issue press releases, take decisions, or speak about operations in the Free Syrian Army's name, except for the FSA command inside Syria," the group's spokesman Colonel Qassem Saadeddine told Agence France Presse.

Syrian troops resumed their shelling of the Houla region on Thursday, killing at least one person at the site of a massacre of 108 people last week, the Syrian Observatory for Human Rights said.

"A boy was shot dead today by a sniper," Britain-based Observatory chief Rami Abdel Rahman told Agence France Presse.

Portugal has declared Syria's Paris-based ambassador Lamia Shakkur persona non grata, following a wave of sanctions by Western countries against Syrian diplomats, the foreign ministry said Thursday.

Shakkur, who also represented Damascus in France and Switzerland, has already been ordered to leave by Paris and declared persona non grata by Bern, in the wake of the recent massacre at Houla in central Syria.

U.S. Secretary of State Hillary Clinton on Thursday criticized Russia's resistance to U.N. action on Syria, warning that its policy could contribute to a civil war.

The Russians "are telling me they don't want to see a civil war. I have been telling them their policy is going help to contribute to a civil war," she told a mainly student audience on a visit to Copenhagen.

President Michel Suleiman urged the Syrian authorities on Thursday to release the two Lebanese farmers who were kidnapped a day earlier in the border region of al-Abboudiyeh as the Syrian army abducted another citizen later on Thursday.

The Syrian army kidnapped Yehya Mohammed Fleiti in the border town of Arsal on Thursday afternoon.