The National Organization for Human Rights in Syria says tank shells and gunfire killed 13 people including a child in the southern village of al-Haraa Wednesday.  Rights activists say the Syrian military also attacked several other villages near the southern town of Daraa, where the uprising began in mid-March before spreading nationwide. 

In the west, rights activists say Syrian tanks and snipers killed at least six people in the Bab Amr neighborhood of Homs, the country's third largest city. Syrian forces have surrounded Homs as part of a security operation that began Monday. 

Syria's state news agency says Syrian troops attacked what it calls "armed terrorist gangs" in Bab Amr and the southern region of Daraa Wednesday.  It says the fighting killed two Syrian soldiers and wounded five others. The agency says Syrian troops also arrested dozens of armed fighters and seized weapons and ammunition.

The U.S. State Department sharpened its criticism of the Syrian crackdown Wednesday, accusing Damascus of engaging in "barbaric" and "repressive" measures that amount to "collective punishment of innocent civilians." 

Spokesman Mark Toner said the Syrian government needs to realize that the "window is narrowing" for it to change course toward "meeting the legitimate aspirations" of the Syrian people. 

Syrian rights activists say the number of people killed across Syria in the anti-government uprising ranges from 600 to 700. There is no independent confirmation of casualty figures because Syria has banned most international journalists from the country. 

A senior U.S. official later told VOA that the tougher State Department language is partly a response to a Syrian presidential adviser's recent claim that U.S. statements on Syria were "not too bad." The adviser, Bouthaina Shaaban, made the comment in a New York Times interview published earlier this week. 

The U.S. official also said Syria's actions against protesters are "reaching an untenable point."

A bipartisan group of U.S. senators introduced a nonbinding resolution Wednesday, urging President Barack Obama to "speak out directly and personally to the people of Syria" as a show of U.S. support for the protests. 

The senators, led by Independent Joe Lieberman, also condemned human rights violations in Syria and welcomed Mr. Obama's authorization of targeted U.S. sanctions against Syrian officials blamed for those abuses. 

In other developments, the Syrian Observatory for Human Rights says Syrian security forces arrested leading dissident Mazen Adi of the People's Democratic Party on Tuesday. Syrian authorities have detained thousands of protesters and dissidents in recent weeks in a bid to crush the uprising. Some have been released. 

The London-based rights group says Syrian authorities have released about 300 people who were detained in the coastal city of Banias, where government forces began a crackdown on opposition protesters last week. It says the authorities made the detainees sign a pledge to stop demonstrating before releasing them. 

In an apparent gesture to the opposition, the Syrian government formed a commission Wednesday to draft a new election law. Mr. Assad has announced several reforms in recent weeks, including the lifting of a 48-year state of emergency, while also intensifying his crackdown on the protests. 

Mr. Assad's cousin Rami Makhlouf is vowing the Assad family will "fight until the end." He made the comment in an interview with the New York Times  published Wednesday. 

U.N. Secretary-General Ban Ki-moon urged President Assad Wednesday to "desist from excessive force and mass arrests of peaceful demonstrators" and to heed calls for democratic reforms. Speaking at a news conference in Geneva, Mr. Ban also called on Syria to allow humanitarian workers to enter Daraa.