The new TSB bank has run into immediate technical difficulties on the first morning of its re-launch, with customers unable to access its website, tsb.co.uk.

Customers tweeted that they were unable to access their online banking through the new TSB site for a period of time. Both TSB and Lloyds customers were said to be affected by the outage, which occured after Lloyds Banking Group's chief executive, Antonio Horta-Osorio, promised that the transition would be "seamless" for all customers.

Hugh Watson @hmlwatson34m commented: "TSB now split from Lloyds. Just tried to log in to my account Lloyds (TSB). Online banking not available. Bad start to the new dawn."

In response to complaints, TSB said on its new Twitter account that the site is now back up and running properly, and apologised for "any inconvenience" caused by the outage.

A Lloyds spokesperson confirmed that customers were temporarily unable to access their online accounts.

"We are experiencing an issue with our internet banking service this morning, which has affected the ability of some customers to log on successfully," a statement read.

"We are working to resolve this as quickly as we can and we apologise to customers for the inconvenience this will have caused. Our branches, telephone banking and cashpoint facilities have not been affected in any way."

The TSB website went live in August, with customers only being able to log into the site from 8 September, ahead of the full launch of the bank today, as it separates from Lloyds to operate under its original name. The accounts of five million customers were being automatically transferred from Lloyds to TSB.