Malaysia’s leading political blog was being blocked on Thursday in what was seen as a crackdown on websites credited with contributing to government losses in this year’s general election.

The move came as Anwar Ibrahim, the former deputy prime minister, was being sworn in as the new opposition leader following a by-election victory this week that returned him to parliament for the first time in a decade. Mr Anwar vowed to mount a no-confidence vote against the government by mid-September.