Employees of the state-run National Commerce Bank realized only late Sunday that the branch in the Bishalbazar commercial area had been robbed when it was closed over the weekend, police said.

"The robbers, who we suspect are Maoists, broke the lock on the bank. We estimate they took around 50 million rupees (about 680,400 dollars)," a senior police officer told AFP.

Police were unable to find the thieves even though a police station lies only 100 meters (yards) away from the bank.

It would be the first known attack on a prominent bank in Kathmandu by the Maoists, who have regularly looted provincial banks to fund their seven-year "people's war" aimed at overthrowing the monarchy.

The Bishalbazar area is home to some of Kathmandu's elite shops and by day is packed with hundreds of shoppers.

The Maoist insurgency has claimed more than 8,200 lives since 1996, according to security forces' figures, or around 8,900 according to Kathmandu-based human rights activists.