The Metropolitan police were accused of using "Gestapo" tactics during the cash-for-honours affair yesterday by Sarah Helm, the wife of Jonathan Powell - Tony Blair's former chief of staff.

Mrs Helm, a respected journalist and author, broke ranks with the others in Mr Blair's inner circle to condemn the heavy-handedness of police and, in particular, a dawn raid on Ruth Turner, former No 10 aide.

Writing in a Sunday newspaper, she said: "I know one shouldn't make these comparisons, but I was writing about Nazi Germany right then and I couldn't help think: Gestapo tactics! Pick on the vulnerable, preferably a single woman, living alone. No matter that you may have nothing on her that will ultimately stand up in court - give her a scare."

The raid on Ms Turner's home had infuriated her colleagues at the time, but nothing was said on the record.

Mrs Helm wrote: "As if she were some kind of street criminal, ready to scarper, Ruth's home was swooped on by (Assistant Commissioner John) Yates's men and she was forced to dress in the presence of a female press officer. Then there was a tip off to the press."

Mr Blair's reputation was damaged over the allegations, although he maintained no-one had done anything wrong.

Sir Christopher Evans, the only lender arrested during the investigation, complained yesterday that the Labour Party had abandoned him and other suspects at the centre of the scandal.

Making what was considered a thinly veiled attack on Gordon Brown, Sir Christopher said: "I know people are obviously very reluctant to get embroiled in any of these things when the police are involved but I think (senior Labour figures) should stand up for their principles."

Sir Menzies Campbell, the leader of the Liberal Democrat who faced his own embarrassments over party funding, called for a "wholesale review" of the laws on peerages, and he argued the case for a strengthened Electoral Commission.

Speaking to BBC News, he said: "We need to have proper regulation that's properly enforced by a revamped, strengthened Electoral Commission, and of course right at the heart of this is to have reform of the House of Lords so that it's either wholly, or mainly, an elected chamber."

The Prime Minister has said proposals to reform party funding are already on the table.