Customers of the peer-to-peer lending and investment service Zopa have taken to social media to complain that they have been locked out of their online accounts, with some told that their accounts have been 'suspended'.

Zopa has apologised to a number of angry customers online, some of whom said they've been locked out of their accounts since Friday, and has blamed system maintenance work. The firm told told MoneySavingExpert it's "in the process of re-opening the small number of investor accounts affected by the maintenance" and will update customers further on Tuesday.

Customer Tom Arran tweeted what he said was a screenshot of a message he received when trying to log into his Zopa account:

Here are some of the other tweets we've seen:

What does Zopa say?

A Zopa spokesperson said: "We’re currently in the process of re-opening the small number of investor accounts affected by the maintenance and will be sending out communications to our customers tomorrow [Tuesday] morning."

We've seen a number of responses from Zopa to customer complaints on Twitter, such as the following response to Tom:

If you've been affected by the problems, let us know at news@moneysavingexpert.com.