The personal details of almost 150 residents have been leaked in Islington Council’s third data breach in less than a year.

In the latest gaffe, less serious than the other two, the private email addresses of 140 people were revealed when a council officer sent out an email on Monday afternoon.

The council has now been referred to the Information Commissioner three times in recent months and could face a fine of up to £500,000.

A spokesman said: “Instead of using the ‘bcc’ field, as is our policy, we used the ‘cc’ field, meaning the recipients’ email addresses were visible. No personal information was disclosed.”

In April, the contact details of people who had complained about a gang loitering on the Andover Estate, in Holloway, were sent to the thugs themselves – and some frightened people had to be re-homed.

Then in September personal details of 2,400 residents, including age, gender and sexuality, were placed on a public website by the council.

After the first two errors town hall chiefs promised to train staff more thoroughly to avoid further slip-ups.

Cllr Terry Stacy, leader of the opposition Lib Dem group, said: “It’s yet another data blunder by the council. We were assured it would never happen again, but surprise surprise it has. This council clearly cannot be trusted with people’s private information.”