Almost half the British public believes the Russian government interfered in the EU referendum and last year’s general election, according to a poll. The latest Opinium poll for the Observer found that 49% of voters think there was Russian interference in the Brexit referendum, with 23% disagreeing. Some 47% believed Russia interfered in the December general election.

The poll findings come after the long-awaited publication of the report into Russian interference by parliament’s Intelligence and Security Committee last week. It found that the government had not attempted to investigate potential Russian interference in the referendum. It said the UK had “badly underestimated” the Russian threat.

Opinium asked people whether they thought there was any involvement from Russia in the last three general elections, the EU referendum and the Scottish referendum. For each, the public were more likely to think that the Russian government had interfered than that it had not.

Two-fifths (40%) thought Russia had interfered in the 2014 Scottish independence referendum. Remainers were more likely (63%) to think that the Russian government interfered in the EU referendum than Leavers (39%).

Asked about the 2019 general election, 70% of Lib Dem voters and 62% of Labour voters believed the Russian government interfered, compared with 39% of Conservative voters. However, even Conservative voters were more likely to believe that the Russian government interfered in that election (39%) than not (33%).

Meanwhile, the poll found that the Tory lead over Labour had halved this week, from 8 points to 4 points. The Conservatives slipped two points to 42%, while Labour increased two points to 38%. The Lib Dems (6%) and Greens (4%) remain unchanged on last week.

The government’s net approval rating for the handling of the pandemic worsened and has now dropped to a net approval of -15. Disapproval rose from 43% last week to 46% this week, while approval has fallen from 38% last week to 32% this week. Boris Johnson’s approval rating remains in negative figures, with 36% approving and 45% disapproving of his performance. His net rating had dropped from -4 last week to -8 this week. Opinium polled 2,002 people online from 23-24 July.