Scotland Yard's investigation into "cash for honours" allegations against the British government has again reached into the heart of Downing Street with the arrest of a senior aide to prime minister Tony Blair on suspicion of perverting the course of justice.
Officials at 10 Downing Street were surprised by the early morning arrest of political adviser Ruth Turner, who was questioned for several hours at a London police station before being released without charge on police bail.
Ms Turner - Mr Blair's "gatekeeper", who became the fourth person and first salaried official to be arrested in the inquiry - released a statement through Number 10 last night rejecting "any allegations of wrongdoing of any nature whatsoever".
Having already been interviewed under caution last September, Ms Turner said: "I have already given the police two lengthy interviews and made clear that I was happy to speak to them again at any stage. I have been completely open with the police and will continue to co-operate with them fully."
And she won firm backing from Mr Blair, who declared: "Ruth is a person of the highest integrity for whom I have great regard and I continue to have complete confidence in her."
However, Scottish National Party MP Angus MacNeill, who triggered the police inquiry into alleged offences under the Honours (Prevention of Abuses) Act 1925, suggested the arrest underlined "the seriousness of the situation facing Downing Street" and that "water is now lapping around Tony Blair's neck".
Downing Street had assumed Mr Blair was in the clear after police investigating the alleged link between secret pre-election loans and four nominations for peerages interviewed Mr Blair last month without arresting or cautioning him. However, police said yesterday's "new development" would require additional investigations by the Specialist Crime Directorate.
Ms Turner's arrest "on suspicion of perverting the course of justice" inevitably sparked speculation that police may be turning their attention to any possible cover-up.
Downing Street said Ms Turner remained in her post and that people should await the conclusion of the police inquiry before reaching any conclusion. However, the Liberal Democrats charged: "As this sorry saga continues, it is clear the Blair government is in its dog days, increasingly mired in sleaze."