Bosses at The Syndicate are offering the massive sum in return for information which leads the conviction of the thieves or the recovery of the stolen money – thought to run into six figures.

The break-in happened on New Year's Day.

Two masked burglars used duplicate keys to enter the club through a staff entrance on King Street.

Once inside the closed venue, one of the thieves – armed with a crowbar – snatched the cash.

Paul Kinsey, chief executive of Nexum Ltd which owns the club, said staff had been left shocked by the break-in.

Mr Kinsey said: "A very substantial amount of money was taken by someone who seemed to have a very intimate knowledge of the club.

"There is a general feeling of shock among the staff who are a very close knit team. It's the type of situation that creates mistrust and it's very difficult with the possibility that it may have been someone they know well.

"Police are following a number of lines of inquiry and they are doing a great job.

"Hopefully the reward will make people sit up and take notice and have a think if they were in the area on the night. Any clues could be vital."

Both offenders were carrying bags. They are thought to have first entered the club shortly before 11pm on January 1, leaving with some of the money around half an hour later.

Detectives believe they then returned at around 2.45am, taking more money out of the club.

Det Sgt Paddy Dowling, who is leading the investigation, is keen to speak to two females who were walking along King Street after 2am and may have seen the offenders leave.

Det Sgt Dowling said: "These two girls may be vital witnesses and could have seen the offenders who we believe left at around the time they walked past. I urge them to come forward and speak to us as soon as possible.

"We also want to speak to anyone else who may have been town near the time of the offence, such as taxi drivers, who may have seen something noticeable or unusual that could help."

Anyone with information is urged to call Blackpool Police on (01253) 293933 or Crimestoppers on 0800 555111.