Thieves used a large drill to break into a safe at a high street bank branch in western Germany and steal an estimated €30m (£26m; $35m) in cash and valuables, police have said.

A police spokesman likened the break-in to the Hollywood heist film Ocean's Eleven, telling AFP news agency it was "very professionally executed".

During the heist at Sparkasse savings bank in the city of Gelsenkirchen, thieves broke open more than 3,000 safe deposit boxes containing money, gold and jewellery. 

Gelsenkirchen Police said they became aware of the crime after a fire alarm was set off in the early hours of Monday morning.

Currently, no arrests have been made and the perpetrators remain at large.

Police said the thieves had used the "quiet Christmas days" to rob the building on Nienhofstrasse in the Buer district.

Initial investigations suggest they gained access to the bank, and escaped, via an adjacent parking garage.

Witnesses have reported seeing several men carrying large bags in the staircase of the garage overnight on Saturday into Sunday. 

Police said video footage shows a black Audi RS 6 leaving the garage, on De-La-Chevallerie-Strasse, early on Monday morning.

The hole into the underground vault room was discovered when a fire alarm went off in the early hours of Monday, and police and the fire brigade searched the building.

Affected bank customers have been asked to contact Sparkasse bank, which has set up a hotline. Police secured the entrance of the branch on Tuesday after a large number of customers gathered outside demanding information.

A message on the bank's website said the branch would remain closed on Tuesday following the break-in.

Sparkasse said 95% of customers' safe deposit boxes had been forced open by the thieves, so the likelihood they were affected is "very high". 

It added that the contents of each compartment are insured up to €10,300 and told customers to check if they had additional coverage through their home insurance.