The United Nations' senior adviser on Syria, Jan Egeland, has said that nearly three million civilians will be caught in the crossfire if an offensive is launched on Idlib.
Speaking on RTÉ's Six One News, he said there had been an enormous build up of forces around Idlib for many weeks now.
"It's like a countdown to an enormous battle and everybody seems to forget that there are many more babies inside than so-called terrorists."
Mr Egeland said that he had received a report today that a hospital in the region had been attacked.
He said: "In this war on terror, the warfare becomes more and more indiscriminate."
Mr Egeland said that in Syria there are more hospitals that have been struck than in any other recent war.
"In Syria there are more hospitals hit than in any other place in any other recent war, so it seems that in cases they have been attacked. But when you try to find out why, it's disputed whether this was really a hospital or whether it was misused by a rebel group."
He said: "This has become a very dirty war where all armed actors routinely commit crimes and we have to do all we can to get some sanity and civilisation into this and it's not too late to avert the attack on Idlib."
Mr Egeland called for local deals to be struck with militant groups to reach a ceasefire and avoid an all-out assault.
"There can be local deals, there can even be deals with so-called listed terrorists.
"There have been many local agreements before in Daraa, in Quneitra recently countless civilian lives have been spared because armed men on each side agreed to end the battle.
"I'm very nervous for this talk that we need to go in and kill every one of these terrorists. It would mean enormous warfare in a civilian place," said Mr Egeland.