Human rights group Amnesty International reported Friday that at least 55 people were believed to have been killed since protests erupted in and around the southern Syrian city of Daraa a week ago.
The human rights organization chastised the Syrian government, saying in a statement that "security forces again opened fire on protesters in al-Sanamayn and carried out arrests in Damascus, according to reports on Friday, a day after the authorities pledged to investigate the violence."
Earlier, UN Secretary-General Ban Ki-moon called for "maximum restraint" by Syria, in a telephone call with President Bashar Assad, whose forces have killed dozens of pro-democracy demonstrators.
A statement issued by Ban's office said he told Assad that "governments had an obligation to respect and protect their citizens fundamental rights."
Ban "urged maximum restraint by the authorities and expressed his hope in a meaningful response to the expression of legitimate concerns," the statement said.
Amid a general wave of unrest in the Arab world, protests have spread across Syria, challenging the rule of the Assad family. Clashes intensified on Friday, with at least 23 reported dead in clashes in various locations throughout the country in what anti-government protesters have called 'Friday of Dignity'.
The United States has also condemned the harsh Syrian crackdown, calling on the Syrian government to stop violence against demonstrators and the arrests of human rights activists, White House spokesman Jay Carney said on Friday.
"We strongly condemn the Syrian government's attempts to repress and intimidate demonstrators," he told reporters.
Turkey also issued a statement Friday, calling on Syria to make good on promises of economic and social reform as soon as possible in the face of growing unrest.
In the statement, Turkey's Foreign Ministry regretted casualties in the violence spreading through its southeast neighbor and called for calm on the part of families that had suffered casualties.
"We welcome the statements of Syrian officials on starting work for reform on social and economic issues to meet the Syrian people's legitimate demands and expectations," the statement said.
"It is of great importance that the necessary work is completed soon and the decisions are implemented without losing time."
Turkish officials have been guarded in their comments on events in Syria. Relations between the two countries have improved markedly since the AK Party has been in power, while Turkey's old friendship with Israel has cooled.
Prime Minister Tayyip Erdogan said this week he had spoken to President Bashar Assad during his last visit to Syria about the upheavals in the Arab world and had urged him to find a more democratic path.
"I said very clearly and very openly that Mr Assad should take a lesson from what has been going on in other countries in the region and without trying to use same manner, should find a way out which is much more democratic."
Erdogan said he warned Assad it would be dangerous if any social unrest in Syria assumed a sectarian dimension.
The Foreign Ministry statement said Turkey was monitoring developments closely in Syria and offered condolences to the bereaved.
"We wish patience to families of those who lost their lives, send our condolences, and wish the best of health to those injured," it said.
A Syrian opposition leader implored the international community Friday to intervene to stop "the massacres against civilians by President Bashar Assad's regime" in protests across Syria.
"There are killed and wounded and those who are arrested in all the provinces," he told Reuters by telephone from Canada, referring to protests that spread beyond the southern town of Deraa on Friday challenging Assad's rule.
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