The United Nations says Syria is refusing “unhindered” access for humanitarian aid.

U.N. humanitarian chief Valerie Amos said Friday that Syrian officials “asked for more time” to consider a deal that would allow the U.N. to help the victims of the ongoing government crackdown on dissent.

Amos told reporters in Ankara that Syrian officials agreed to a “limited assessment exercise” to get some information about the plight of those affected by the violence. She spoke after touring refugee camps along the Turkish-Syrian border, where at least 11,000 Syrians have sought refuge in the nearly year-long uprising.

The discussions were held as former U.N. Secretary-General Kofi Annan prepares to visit Syria Saturday in search of a political solution to the crisis. Mr. Annan, the new U.N.-Arab League envoy to Syria, has warned against arming rebel forces, saying foreign intervention would make the situation worse.

Syrian opposition groups say at least 19 people died Friday as thousands took to the streets across the country to rally against the government of President Bashar al-Assad. The Syrian Observatory for Human Rights said most of the deaths occurred in the Homs, the city that has been a focus of the government's crackdown against protest.

Despite the continued bloodshed, China is voicing support for Annan's mission, saying it hopes that “impartial mediation” can result in peace talks. China, along with Russia, has twice vetoed U.N. Security Council proposals that would have put pressure on Mr. Assad's government to end the conflict.

However, some foreign diplomats say the end of the Assad government may be in sight.

Germany Foreign Minister Guido Westerwelle said Friday that “the collapse of the Assad regime has started and will continue. No country can be led with atrocity and oppression.”

There are also new calls to help arm the Syrian opposition.

U.S. Senator John McCain accused Russia and Iran of fueling the bloodshed by proving the Syrian military with weapons. He told Alhurra TV Thursday the U.S. and other countries should use air power to take out the military's defenses.

The U.N. estimates that Syrian forces have killed well over 7,500 people since the anti-Assad uprising began a year ago. The government blames “terrorists” for the unrest, saying that 2,000 of its security forces have been killed in the conflict.