Syria's ruling Baath party has replaced its top leadership in a surprise move, while UN head Ban Ki-Moon called on all parties in the war to observe a truce during the Muslim holy month of Ramadan.
Meanwhile in Turkey, interim Syrian rebel prime minister Ghassan Hitto announced his resignation Monday on a day of political manoeuvring.
The developments came as troops loyal to President Bashar al-Assad advanced into the rebel-held Khaldiyeh district of Homs on the 10th day of an assault there.
The Baath party's central committee published the names of 16 members of the new leadership, which included none of the party's old chiefs with the exception of Assad, who will remain secretary general.
The ruling party reshuffle was its first since 2005 and Assad urged the party to "develop" and work more closely with the people to help end the country's 27-month war, state media said.
Among the incoming party leaders are parliament chief Jihad al-Laham and Prime Minister Wael al-Halqi.
"The party must develop in step with reality on the ground, and promote a culture of dialogue and voluntary action by the people," Assad said, cited by state news agency SANA.
He added that the party needed "to put in place new... criteria for the selection of party representatives, in order for them to be able to achieve (society's) objectives".
In New York UN chief Ban was more concerned with the continued bloodshed, calling on all Syrian parties to observe a truce during Ramadan.
"I am calling for every military unit of the regular army and the Free Syrian Army, for every person holding a gun, to stop fighting and offer this month of peace as a collective present to their people," he said in a statement.
He added in his "Ramadan appeal" a call for the release of detainees.
Bassam Abu Abdullah, director of the Damascus Centre for Strategic Studies, said the Baath party overhaul was the result of deep-seated party discontent.
"There has been a lot of criticism from within the base towards the leadership, which has been accused of being inflexible, both before and since the crisis," he said, of the uprising.
A second analyst noted the changes presaged a younger leadership that would be "more open to the international community".
The Baath party has been in power since March 8, 1963.
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The move comes against the backdrop of the ongoing conflict in Syria, which began in March 2011 with peaceful anti-government protests but has become a bloody civil war estimated to have killed more than 100,000 people.
In Istanbul, Turkey, as the main opposition National Coalition ended a five-day meeting interim rebel premier Hitto announced his resignation, which the Coalition accepted.
Hitto quit nearly four months after his appointment and after failing to form a government.
His decision came two days after secular dissident Ahmad Assi Jarba was chosen to lead the opposition.
Jarba is seen as close to Saudi Arabia, which opposed the choice of Hitto to head the interim government in March.
Dissidents say Hitto, who is close to the opposition's Islamist ranks and who was backed by Qatar, was unable to work because of divisions within the Coalition.
Hitto said he resigned in order "to help... the Coalition's new leadership to act according to its political vision, especially with regards to the interim government and its executive functions".
In a statement, the Coalition said "it will start accepting candidacies for the post of prime minister in 10 days' time".
On the ground, the army pressed a fierce assault on besieged districts of the central city of Homs, dubbed "the capital of the revolution" by activists.
State media reported two car bombings in a regime-held area in the city, and the Syrian Observatory for Human Rights reported five killed in one of them, in the Akrameh district.
Most residents of Akrameh are, like Assad, members of the Alawite community.
"The ruthless campaign against Homs is continuing for the 10th day in a row" activist Abu Bilal told AFP via Skype.
"Regime forces have been able to enter parts of Khaldiyeh after heavy shelling and scorched-earth tactics."
He said the assault was the fiercest in Homs since the uprising began.
The United Nations has estimated some 2,500 people are trapped amid the fighting there.
Meanwhile, Syria's ambassador to the UN Bashar Jaafari said Damascus has invited two senior UN officials for talks on the alleged use of chemical weapons in the conflict.
The UN says Damascus has barred its investigators from examining claims by Britain and France of chemical weapons use by regime forces at Khan al-Assal and Homs last December.