Fall in election advertising spending
The amount spent on advertising by political parties went down in May's general election campaign compared with previous years, the Electoral Commission says.
But the regulator said spending on market research and "unsolicited material" for voters went up.
It said the changes might be down to a move away from traditional campaigning to a more targeted, online approach.
General levels of spending were similar to the 2010 general election.
In its campaign spending report for the 2015 general election, the commission said spending on advertising was £6.9m, compared with £9.2m in 2010, with the amount spent on campaign broadcasts down from £1.5m to £806,000.
At the same time, market research spending went up from £1.8m to £7.6m with unsolicited material up from £12.4m to £15m.
The commission also called for new powers to regulate spending at elections.
Its director of party and election finance Bob Posner said: "The law currently stops short of giving the commission the power to enforce candidates' spending rules and only the police can investigate if there's a problem.
"It's time to end that anomaly and give us the power to investigate and sanction.