TORONTO -- A widespread problem at Bank of Montreal's (TSX:BMO) automated systems Friday briefly left customers unable to withdraw money from bank machines or access online banking.

The big Canadian bank said an outage began around 10:30 a.m. ET and customers were able to regain access to automatic teller machines and at points of sale just before 1 p.m.

However, a problem with online services persisted into the evening and was resolved shortly after 6 p.m., the bank said.

"We sincerely apologize to customers who were inconvenienced by service interruptions earlier today," it said.

Earlier in the day several customers from Vancouver to Toronto to Quebec tweeted that they were unable to make purchases using their debit and credit cards.

Shares in the bank fell 26 cents to $58.92 in Friday trading on the Toronto Stock Exchange.