The Conservative Party spent £15 million more than Labour last year, according to official figures.
The Tories spent £49,205,000 during 2010, including on the general election campaign, while Labour spent £33,840,000, the Electoral Commission said.
As the independent party funding watchdog published the financial accounts of the main political parties, the British National Party (BNP) and Christian Party were warned they could face substantial fines for failing to submit their accounts on time.
The figures show that the Conservative Party received income of £43,143,000, suffering an overall loss over 2010, while Labour received £36,270,000.
The Conservative Party in Northern Ireland also spent £391,359 and received £408,127.
And the Liberal Democrats spent £9,973,077 over the year, with an income of £9,637,354.
Peter Wardle, chief executive of the Electoral Commission, said: "The rules on party funding are intended to ensure that voters can see where political parties get their funding from, and how they spend it.
"The 2010 statements of accounts which we have published today help to provide transparency about the finances of the larger parties and their organisations, covering the period during which the campaigns for the 2010 UK general and local elections took place."
Mr Wardle hit out at the failure of the BNP and Christian Party to submit their accounts to the Commission.
"The majority of parties and accounting units have complied with the law by submitting their accounts on time - however, despite the guidance and advice we offer to help parties comply with the law, two parties have yet again failed to provide accounts on time," he said.
"This is not acceptable. We have commenced formal case reviews into the circumstances. If we are satisfied that the rules have been broken and the parties concerned do not have a reasonable excuse, we will use our new powers to impose sanctions in accordance with our published enforcement policy, to ensure future compliance with the law."
The watchdog has a range of sanctions at its disposal, including issuing substantial fines and serving compliance notices. Political parties with a gross income or total expenditure of over £250,000 were given until July 7 to submit their 2010 accounts.