LONDON (Reuters) - No criminal charges will be brought over allegations of expenses fraud by Prime Minister Theresa May’s Conservatives during their 2015 election campaign, prosecutors said on Wednesday, removing a cloud over the party weeks before a new election.

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According to media reports, more than 30 lawmakers and their electoral agents were under investigation over their spending, which is governed by tight, complex rules. The Crown Prosecution Service (CPS) said it had considered evidence from 14 police forces across the country.

“We reviewed the files in accordance with the Code for Crown Prosecutors and have concluded the tests in the Code are not met and no criminal charges have been authorized,” said Nick Vamos, the CPS head of special crime.

Opinion surveys before the 2015 election had predicted a tight result with no clear victor, but the Conservatives under then-leader David Cameron secured an absolute majority of 12 in the 650-seat parliament.

Police investigated whether expenses incurred by activists on the Conservatives’ “Battle Bus”, sent to campaign in closely-contested seats, were deliberately not declared on the local candidate’s expenditure returns but recorded as a national cost instead, to avoid breaking spending limits.

The Electoral Commission, the independent election watchdog, in March fined the Conservatives a record 70,000 pounds ($91,000) for breaking rules by incorrectly reporting its spending, but the CPS said it would be impossible to prove deliberate wrongdoing.

“Although there is evidence to suggest the returns may have been inaccurate, there is insufficient evidence to prove to the criminal standard that any candidate or agent was dishonest,” Vamos said.

THREAT OF DISQUALIFICATION

Anyone found guilty of breaking election rules can be fined or imprisoned. May had faced the prospect of her slim parliamentary majority being whittled down if any of her lawmakers had been successfully prosecuted, which would have disqualified them from office.

One veteran Conservative Party member, involved in election campaigns for more than two decades, told Reuters her surprise move last month to call an election was the best way of minimizing any potential impact from the police investigation.

Polls suggest that May is on course to win a landslide victory on June 8 and boost her majority to about 100 seats.

“After a very thorough investigation, we are pleased that the legal authorities have confirmed what we believed was the case all along: that these Conservative candidates did nothing wrong,” said Conservative Party Chairman Patrick McLoughlin.

“These were politically motivated and unfounded complaints that have wasted police time. We are glad that this matter is finally resolved.”

However, Tim Farron, leader of the small Liberal Democrat Party, which was in coalition with the Conservatives until suffering heavy losses in 2015, said there was a cloud over British politics, and that those with the most money had an unfair advantage.

“The Conservative Party appears to have stayed right-side of the law by the letter of it, but has driven a battle bus and horses right through the spirit of it,” he told Sky News.