UK Online has announced that a technical issue means it is currently unable to sign up new customers to its broadband services.
In a statement to ComputerWorld UK, the Sky-owned broadband provider claimed it is had been hit by a problem which means it can no longer register internet users to its packages.
No date has yet been put forward as to when the issue, which has not been named, will be resolved.
However, the company added that subscribers already on the service have nothing to worry about.
"This does not affect existing customers and the UK Online network is completely unaffected," it claimed.
UK Online services run over a network which covers 70 per cent of homes and small businesses, while speeds of up to 16Mb and unlimited usage allowances are available through its products.
It was acquired by rival broadband provider Sky, which had a market value of £9 billion in 2005.