LONDON (Reuters) – A cyber attack on email accounts of British lawmakers last month is likely to have been by amateur or private hackers rather than state-sponsored, European government sources said.

The private email accounts of up to 90 of the 650 members of Britain’s House of Commons were targeted in late June, with some news reports suggesting that the attack was carried out by a foreign government, such as Russia.

However, cyber security experts had found that the hackers only managed to access accounts of lawmakers who used primitive and easily discovered passwords, the sources, who are familiar with the investigations into the attacks, said.

It remains unclear who did carry out the attack, they added.

Investigators hope the hack will convince politicians and other public figures to use more sophisticated passwords for their email and other online activities.

British authorities are not commenting publicly on the progress of investigations, but an official cautioned after the hack was discovered that “cyber threats to the UK come from criminals, terrorists, hacktivists as well as nation states.”

(Reporting by Mark Hosenball; Editing by Alexander Smith)