The Conservatives spent more than £16 million at the 2019 general election, new figures show.
The Electoral Commission revealed the governing party spent £16,486,871 across the country to win its 80-seat majority.
The biggest chunk of the money, £5,818,998 went on “unsolicited material to electors”, the Electoral Commission said.
Marketing and canvassing cost £4,471,937, and advertising came in at £3,011,665.
Rallies and other such events saw £529,650 spent on them.
Figures for the Labour Party have yet to be published as its financial submissions to the commission were late due to the coronavirus outbreak.
The report shows that the cost of the SNP campaign was £1,004,952.
Plaid Cymru spent £183,914 in the December election, and the Independent Group for Change paid out £29,556.
UKIP – which failed to win a seat – spent £8,761.
Tom Brake, former Liberal Democrat MP, and recently appointed Director of Unlock Democracy criticised the figures.
“The combination of huge amounts of cash being thrown at elections, with invisible micro-targeting of swing voters in a limited number of marginal seats means our elections are wide open to the highest bidder.
“This has got to stop. For a healthier democracy, we need a fairer voting system and tighter spending controls.”
The figures for other parties will be released in the coming days and weeks.