ARMED robbers escaped with tens of thousands of pounds when they raided a Darwen bank, police revealed today.

But officers have pledged to pour resources into catching the men behind the robbery.

The money was stolen from a cash machine at the Abbey bank, Market Street, when masked robbers armed with machetes and slegehammers burst into the building.

They threatened two Securicor staff who were filling up the ATM in the town centre and forced them to lie on the floor before escaping with a large quantity of cash.

The robbery is the fourth of its kind involving Securicor staff this year -- following on from robberies at Lloyds Bank, Blackburn, last month; Blackburn Road post office, Accrington, in July; and HSBC Bank, Blackburn, in February.

But police leading the investigation into the recent incident said they are not automatically linking it with others.

Inspector Ian Critchley said: "I am co-ordinating the inquiries into the other incidents as well and can assure people that if there are any links we will investigate it thoroughly.

"We will hopefully have some CCTV evidence of the two robberies from last month which we can show people to try and identify those involved.

"We are concerned about the amount of robberies in business properties particularly in cash deliveries and we are maximising our resources in relation to the investigations into them.

"And we are making progress in the others."

The men, wearing balaclavas, followed the security staff into the bank at around 7pm.

They threatened them with the machetes before smashing their way into the cash machine and stealing three cash boxes and a large amount of money running outside to a waiting car.

Insp Critchley said: "The main thing at the moment is seeking assistance from members of the public to see if they've seen the car either before or after the incident.

"The Securicor van was parked outside the bank and a blue BMW 3 series is believed to have pulled up behind it."

The car, which is believed to have the false registration plate ML51 KXM, headed off in the direction of Bolton Road.

The bank was closed until 10.30am yesterday with a notice to customers saying 'closed temporarily due to a robbery'.

Jane Reynolds, a spokesman for Abbey, confirmed that the bank was operating as usual and staff were working with the police with their inquiries.