Libyan Prime Minister Abdurrahim El-Keib, speaking to reporters after meeting US Secretary of State Hillary Clinton in Washington, said his country had been the first to recognize Syria's national opposition council.
"We did it because we felt that the Syrian cause is a good cause. It's people who are raising their voice asking for freedom," El-Keib said.
"As far as training camps, unless this is something that is done without government permission, which I doubt, I am not aware of any."
A senior US official later said he believed El-Keib's comments had firmly denied the existence of any such training camps.
On Wednesday, Russia's ambassador to the United Nations accused Libya of establishing a special training center for Syrian rebels and arming fighters in their battle to overthrow the country's president Bashar al-Assad.
Ambassador Vitaly Churkin told the UN Security Council that Russia had information that Libya was actively supporting the Syrian opposition, which he said was completely unacceptable and undermining the stability of the Middle East.
Russia, which is Syria's main arms supplier and has use of a naval base there, also has repeatedly voiced anger over NATO air strikes that helped Libyan rebels drive Muammar Gaddafi from power last year.
It also has blocked US- and Arab-backed initiatives at the United Nations calling for Assad to step aside, saying it wanted a more balanced approach.
Libya said last month that it would donate $100 million in humanitarian aid to the Syrian opposition and allow them to open an office in Tripoli.
Clinton, in her remarks, praised Libya's progress in building democracy and said Syria's opposition could learn from the Libyan example in mustering a coordinated, unified front to face down a tyrant.
"We are working closely with the Syrian opposition to try to assist them to be able to present that kind of unified front and resolve that I know they feel on their own behalf is essential in this struggle against the brutal Assad regime," she said.
The Obama administration, facing growing calls for stronger action on Syria, is working to build an international coalition to assist Syria's opposition but has rejected military intervention of the kind that occurred in Libya.
Clinton said the United States would seek to assist Libya on governance and security issues as it heads toward June elections for an assembly to draw up a new constitution.
She also said she had brought up yet again the case of Abdel Basset al-Megrahi, who was convicted of engineering the 1988 bombing of a US-bound airliner over Lockerbie, Scotland.
Megrahi remains free in Tripoli after having been returned to Libya in 2009 after being released from a Scottish jail on grounds he was suffering from terminal cancer and the United States has repeatedly urged Libya's new rulers to see that he is returned to prison.
"We know that Libya faces a multitude of challenges but at the same time they have assured us that they understand the sensitivities of this case and they will give the matter the consideration it deserves," she said.
Keib thanked Clinton for US help thus far and said Tripoli hoped for more future cooperation, particularly on Libya's campaign to track down remnants of Gaddafi's regime who have taken shelter outside Libya.
"They have been a nuisance and they have been causing problems and we need them back to give them proper justice and we also need the funds they have stolen from the Libyan people," he said.
Keib dismissed concerns over calls for greater autonomy for eastern Cyrenaica province - home to most of the country's oil - saying this represented "democracy in practice" and was not necessarily a threat to Libya's integrity.
"I disagree with the approach ... because it has to be through the constitution that we are about to create that this issue should be raised," he said.