Syria's President Bashar al-Assad says his government is receiving messages from the US-led coalition battling the jihadist group, Islamic State.
Mr Assad told the BBC that there had been no direct co-operation since air strikes began in Syria in September.
But third parties - among them Iraq - were conveying "information".
The US National Security Council has denied co-ordinating with the Syrian government.
A spokesperson told the BBC that there has been no "advance notification to the Syrians at a military level".
Mr Assad also denied that Syrian government forces had been dropping barrel bombs indiscriminately on rebel-held areas, killing thousands of civilians.
He dismissed the allegation as a "childish story", in a wide-ranging interview with BBC Middle East editor Jeremy Bowen in Damascus.
"We have bombs, missiles and bullets... There is [are] no barrel bombs, we don't have barrels."
Our correspondent says that his denial is highly controversial as the deaths of civilians in barrel bomb attacks are well-documented.
British Foreign Secretary Philip Hammond condemned the president's comments and said that the Syrian government had used crude and indiscriminate weapons against its own people.
He added: "Assad is deluded or lying when he says his military are not murdering hundreds of innocent civilians with the use of barrel bombs."
Analysis: Jeremy Bowen, BBC Middle East Editor
Mr Assad's many enemies will dismiss his view of the war.
For them, he has been in charge of a killing machine that has been chewing Syrians up and spitting them out.
As the war enters its fifth year, the barrel bomb has become the most notorious weapon in the regime's arsenal.
Two or three years ago, I saw the results of what must have been one in Douma, a suburb of Damascus that has been held by rebels since close to the beginning of the war.
Mr Assad insisted that the Syrian army would never use them in a place where people lived.
"I know about the army. They use bullets, missiles and bombs. I haven't heard of the army using barrels, or maybe, cooking pots."
It was a flippant response; the mention of cooking pots was either callousness, an awkward attempt at humour, or a sign that Mr Assad has become so disconnected from what is happening that he feels overwhelmed.
Mr Assad's denial of indiscriminate bombings has also been strongly criticised on social media. Arabic twitter users have been posting photos of the destruction of the rebel-held Douma suburb of Damascus by Syrian government airstrikes.
The hashtag "#Duma_is_being_exterminated" was used over 150,000 times in 24 hours.
Many US-led coalition states have denied co-operating with Mr Assad, whom they have urged to step down since an uprising against his rule erupted in 2011.
But the Islamic State's (IS) seizure of large parts of Syria and Iraq in the past year and its creation of a "caliphate" has prompted officials to consider working with the Syrian leader to combat the group.
Despite this, Mr Assad ruled out joining the international coalition that is seeking to "degrade and destroy" IS.
"No, definitely we cannot and we don't have the will and we don't want, for one simple reason - because we cannot be in an alliance with countries which support terrorism," he said.
He did not give details, but the Syrian government routinely portrays both jihadist militants and members of the political opposition as "terrorists".
Mr Assad stressed that he was not against co-operating over IS with other countries. But he would refuse to talk with American officials, he said, "because they don't talk to anyone, unless he's a puppet", an apparent reference to Western- and Gulf Arab-backed opposition leaders.
"And they easily trample over international law, which is about our sovereignty now, so they don't talk to us, we don't talk to them."
The president did concede, however, that his government had been receiving information indirectly via third parties about sorties by US and Arab warplanes over Syria.
"Sometimes, they convey a message, a general message, but there's nothing tactical," he said, adding: "There is no dialogue. There's, let's say, information, but not dialogue."
Mr Assad dismissed efforts by the US to train and equip a "moderate" rebel force to fight IS militants on the ground in Syria, saying it was a "pipe-dream". He argued that there were no moderates, only extremists from IS and al-Qaeda's affiliate in Syria, al-Nusra Front.
'No indiscriminate weapons'
Elaborating on his denial of the use of barrel bombs, Mr Assad said: "I know about the army. They use bullets, missiles and bombs. I haven't heard of the army using barrels, or maybe, cooking pots."
He added: "There are no indiscriminate weapons. When you shoot you aim, and when you shoot, when you aim, you aim at terrorists in order to protect civilians... You cannot have war without casualties."
Barrel bombs are large cylindrical metal containers filled with explosive and shrapnel.
Human rights activists say they are typically dropped from helicopters - which only government forces are believed to operate - at high altitudes to avoid anti-aircraft fire. At that distance, it is impossible to target with precision, they add.
Mr Assad similarly denied that government forces had used chlorine as a weapon, despite investigators from the Organisation for the Prohibition of Chemical Weapons supporting claims that at least 13 people had been killed in a series of attacks by helicopters on three villages last year.
The president also defended the besieging of rebel-held areas across Syria, which activists say has had the effect of starving civilian residents.
"In most of the areas where the rebels take over, the civilians fled and come to our areas," he said. "So in most of the areas that we encircle and attack, are only filled with militants."