* Six people injured, lives not in danger
* Police launch manhunt, suspect may have crossed into Belgium
* Shootings renew debate on increasing gun crime in France (Adds details, quotes)
By Pierre Savary
LILLE, France, July 1 (Reuters) - A man who was turned away from a nightclub in the French city of Lille returned with a gun and opened fire indiscriminately outside the building on Sunday, killing two people and wounding six others, police said.
The shooting will likely lead to renewed debate about France's gun laws, which were brought into public focus by the killing of seven people in March by an Islamist gunman in Toulouse and a spate of gang murders.
The Lille gunman killed a nightclub employee and a customer, both in their mid-20s, at about 3 a.m. (0100 GMT) before fleeing the scene, said Herve Malherbe, deputy police chief for the northern region.
"The bouncer who knew the man turned him back. The man came back with a heavy calibre gun, possible a Kalashnikov, and started shooting," he said.
Six people were injured, although none of their lives are in danger, public prosecutor Frederic Fevre told a news conference.
He said police from across the region were searching for 32-year-old Faycal Mokhtari, an ex-convict with a history of violent crime, who fled the scene in a car with an accomplice.
Sources said he may have already crossed the border into Belgium where he has home.
"We are putting all are efforts into finding this man as quickly as possible to arrest him and stop him from committing more harm," Fevre said.
The March killings in the southwestern city of Toulouse and gang murders in the Mediterranean port city of Marseille drew attention to the easy availability of illegal weapons in France and their growing use in violent crimes.
The government says there are at least 7.5 million guns in legal circulation which are owned by the state, amateur gun enthusiasts and hunters.
"There are more and more of these heavy calibre guns around and they are getting easier to acquire," said Benoit Lecomte, regional secretary general of the Alliance Police union.
"It's a real problem because while (these guns) can be used for hold-ups, we're also increasingly seeing them being used to resolve issues that used to be solved through fist fights. It's very worrying."
Nobody knows how many illegal guns are in circulation, though experts put the total number of both legal and illegal guns at between 10 and 20 million in a nation of 65 million people.
Already tough gun laws were tightened in March, before the Toulouse shootings, with the approval of longer jail terms and larger fines for anyone caught with an illegal firearm.
Amateur marksmen and game hunters must meet stringent criteria to obtain a gun licence including registering themselves with the authorities, proving they have no criminal record, and passing a psychological evaluation.
There is also a list of about 18,000 people banned from owning guns. (Additional reporting and writing by John Irish; Editing by Mohammad Zargham and Sophie Hares)