LONDON, May 15 (Reuters) - Santander told UK customers on Saturday a technical problem was affecting its services, stopping people from withdrawing funds from some of its cash machines and from logging onto their accounts online.

The bank has 14 million customers in Britain and said in a statement on Twitter it was working hard to fix the problem.

"We’re very sorry for any inconvenience," the bank said.

"You can access cash from other bank's ATMs and at the Post Office." (Reporting by Sarah Young. Editing by Mark Potter)