Home Office contractor Capita sent text messages intended for illegal immigrants warning that they were at risk of being deported; the messages were also received by legal immigrants to the UK.
The ICO originally decided that only a tiny number of people were affected, and so did not take action. However, the organisation now received more evidence, and is considering whether to re-launch its investigation.
Capita said this is a Home Office matter. The department has pledged to look at the processes followed.