By Nick Assinder BBC News Online political correspondent

Tony Blair will undoubtedly be dismayed that his government is now seen by many to be just as sleazy as the last Tory administration.

He entered Downing Street promising to be whiter than white and insisting the trappings of power must not go to his, or anybody else's, head.

The block of flats in question

And the code governing ministerial conduct is regularly pointed to as one of the safeguards.

But that code stresses not only that there should be no impropriety, but also that there should be no appearance of impropriety by ministers.

Thanks to the row over Cherie Blair's property dealing, that issue has been pushed to the fore.

New twist

Downing Street insists there has been nothing illegal or improper in her purchase of the two flats in Bristol. And so far there is no evidence or sign of any evidence, to the contrary.

But does the purchase leave an impression of impropriety. In other words, might ordinary people suspect something dodgy might be going on?

Pressure for Blair statement

At the centre of the new twist in the row is the fact that Cherie Blair used cash from a blind trust - money that had come from the sale of the family's previous home in Islington - to buy the flats in Bristol.

The trust was set up to ensure ministers could not use their inside knowledge to gain advantage in things such as share dealings because they would not know what their money was being spent on.

But in this case, the cash was taken out of the trust by Cherie Blair to buy the two flats, one of which Downing Street has confirmed was an investment - which they hoped to make money on.

Conflict of interest

The question is whether property dealing should be viewed in the same light as share dealing.

There is no doubt that the aim of the exercise was to make a profit. But was there a conflict of interest?

Might Mrs Blair have access to privileged information about what might happen to affect the possible profit from her property?

It seems unlikely, but ordinary voters may not be reassured by the fact that the person who arbitrates on the code is the prime minister himself.

Tony Blair did seek advice on this from the cabinet secretary, but Downing Street will not say whether that was before or after the purchase.

This is, once again, a murky area for the Blairs and it seems likely the pressure for some sort of explanation or statement from the prime minister himself will only intensify.