Iain Duncan Smith has been cleared of any wrongdoing over the employment of his wife as diary secretary in his Westminster offices.

The committee on standards and privileges held an investigation after complaints were handed to parliamentary standards commissioner Sir Philip Mawer by figures including journalist Michael Crick.

It was alleged that while Betsy Duncan Smith received a salary to work as diary secretary in her husband's office, she did not do any work.

These allegations were rejected in a report published on Monday, although MPs pointed to confusion about her role.

She, along with two private secretaries in Duncan Smith's office, should have been paid out of "Short money" - which is given to opposition parties - for their party political work, rather than from his parliamentary staffing allowance.

"Mr Duncan Smith's financial arrangements may not have been ideal in the light of the current official interpretation of the various allowances available to him, but we would not be prepared to find a breach of the code in circumstances where such ambiguity exists," the report said.

Crick was criticised for his information-gathering techniques, which the committee said it had "grave doubts" about.

The journalist accepted the findings but insisted the committee was right to investigate.

"It was absolutely right that this should have been pursued and absolutely right that the commissioner should have looked into it," he said.

"It should be a matter of public record who emplpys which members of their family, what they do and how many days they work," he added.

"There is an extraordinary air of complacency.  I would also ask why MPs think freedom of information applies to the rest of the public sector but not to them."

Duncan Smith himself welcomed the findings.

"I am immensely pleased that after a long and detailed inquiry, the committee and the commissioner have cleared Betsy and I of the serious allegations made against us," he said in a statement.

"I said at the start of the inquiry that we would be exonerated and today we have been.

"This has been a very difficult time for us but now at last it is over and we can look forward as a family to getting on with our lives."