Updated

A prominent lawmaker from Syria's ruling party on Tuesday rejected conditions proposed by the rebel opposition for peace talks, effectively extinguishing the first glimmer of hope in months that Syria's civil war can be resolved through a negotiated solution.

Also Tuesday, fighting broke out between rebels seeking to topple the regime of President Bashar Assad and government forces near a Syrian border crossing with Jordan, injuring 17 civilians.

After 22 months and more than 60,000 dead, Syria's crisis appears to have reached a stalemate, with neither side making significant battlefield gains likely to bring about a military victory any time soon.

The U.S. and other world powers have pushed for a negotiated solution — a bid which appeared to get a boost this week when the head of the opposition's National Alliance said he'd be willing to negotiate with certain figures from the Assad regime "who don't have blood on their hands."

In an interview with Al-Arabiya TV on Monday, Mouaz al-Khatib said the regime must "negotiate with the goal of removing (Assad) from power to spare bloodshed." Khatib has also said the regime must free 160,000 political prisoners and renew the passports of Syrian activists abroad.

On Tuesday, prominent Syrian Parliamentarian Fayez Sayegh told The Associated Press that any dialogue must begin without preconditions. He also called Khatib's number of opposition supporters in Syrian custody "exaggerated," although he did not give an alternate number.

"What is important is for Syrians to meet and agree on common ground for talks," Sayegh said, adding that al-Khatib's proposals, such as the prisoner release, should come "as a result of a dialogue, not before it begins."

Human rights organizations say tens of thousands of opposition leaders, protesters and their families are being held by state security services in Syria.

Khatib first suggested the possibility of dialogue last week in a post on his Facebook page, sparking a wave of criticism from activists and members of his own group who say the regime has killed too many people to play a role in the conflict's solution. Many accused Khatib of acting unilaterally, and he clarified in a subsequent post that he was expressing his personal views.

He explained his position further on Monday, preconditioning the talks on Assad's departure and saying they could spare Syrians more suffering.

"The regime either has to admit that it has pushed the country to a scary state of complications and destruction and now feels this and negotiates to achieve the removal (of Assad) with the least losses or it takes another position," Khatib told Al-Arabiya "All the others issues are less important than this."

He also suggested that there are regime officials the opposition would agree to meet with, mentioning by name one of Syria's two vice presidents, Farouk al-Sharaa. In December, al-Sharaa was quoted as acknowledging that the army could not defeat the rebels and calling for a negotiated settlement.

"Every day that passes, the military and political solution gets more elusive," al-Sharaa was quoted as saying in Lebanon's Al-Akhbar newspaper. "We need to be in a position to defend Syria. We are not in a battle for an individual or a regime."

Al-Sharaa has not made any public comments since the interview's publication.

Al-Khatib's offer followed meetings he had held separately with Russian, U.S. and Iranian officials on the sidelines of a security conference in Munich over the weekend. Russia and Iran are Syria's two closest allies.

Washington hailed al-Khatib's willingness for dialogue, but said the offer should not include immunity for those responsible for killing civilians.

"We've long said that those with blood on their hands in Syria need to be held accountable," State Department spokeswoman Victoria Nuland said Monday, adding that the regime should accept al-Khatib's offer to talk if "it has any interest in peace."

Also Tuesday, fighting between rebels and government troops broke out near a Syrian border crossing with Jordan, leaving 17 civilians — including two Jordanians — wounded, a Jordanian security official said. He spoke on condition of anonymity as he was not allowed to brief reporters.

A rebel spokesman in the area said fighting near the Nassib crossing had intensified over the last two days as rebels make their first serious attempt to seize crossings and military posts along Syria's southern border.

Meanwhile, the United Nations said Tuesday the humanitarian situation in Syria had reached "catastrophic" proportions, with some 2.5 million people lacking food.

Jens Laerke, a spokesman for the U.N. Office for the Coordination of Humanitarian Affairs, said 2 million people have been displaced inside Syria while 4 million need urgent help. Those numbers could rise if fighting continues, he said.

The U.N. says more than 60,000 people have died since the uprising began in March 2011. The revolt began with political protests but turned into a civil war after some opposition groups took up arms to fight a brutal government crackdown on dissent.