Some British MEPs have been pushing for reform of the European Parliament
One of the Tory MEPs at the centre of a row over expenses has been replaced as the party's chief whip in Brussels.
Den Dover denies breaking any rules in paying his wife and daughter a reported £750,000 for work over nine years.
The Tories say the move is unrelated to the issue of expenses and was normal after a change of leader.
On Thursday the party's leader in Brussels, Giles Chichester, resigned after he admitted breaking European Parliament rules on expenses.
Tory leader David Cameron will next week send the party's new financial troubleshooter, Hugh Thomas, to Brussels to launch a clean-up of MEP expenses.
Mr Thomas, who was appointed the party's head of compliance in March, will bring Tory MEPs into line with their colleagues at Westminster by making them publish a regular breakdown of their expenses.
He will also report back to Mr Cameron on any further steps needed to increase transparency, the party said.
Mr Cameron said: "Hugh Thomas has been tasked by me to do all that we can to reinforce the clear message I have sent on the issue of expenses.
"I have said very clearly that MEPs - like MPs - must meet the highest possible standards with accountability and transparency.
"MEPs do of course report to their own separate authorities in the European Parliament. But anyone who flies under the Conservative banner carries a wider responsibility to the reputation of the party."
It come as another Conservative MEP appeared to have breached the rules governing expenses.
John Purvis, MEP for Scotland, has been paying staff in his parliamentary office through a firm, Purvis and Co, of which he is a partner.
A spokeswoman for Mr Purvis said he had been paying staff through the firm for a number of years - and had sought clarification about the regulations in January 2007. She said he did not know if he was in breach of the rules.
Officials were now investigating why Mr Purvis was not given clarification about the rules when he requested it, she added.
On Thursday, Giles Chichester resigned as the Tories leader in Brussels after breaking rules preventing MEPs from paying money into a company with which they are linked.
The MEP for South West England and Gibraltar said he had not realised the European Parliament's rules had changed and vowed to clear his name.
The breach came to light after new guidelines for Tory MEPs drawn up by Mr Chichester himself came into force.
His replacement as leader, Philip Bushill-Matthews, has told Mr Dover he will be replaced as chief whip by Richard Ashworth MEP.
Mr Dover, an MEP for North West England, insists he has not broken European Parliament rules by employing family members - something 23 out of Britain's 79 MEPs do, according to think tank Open Europe.
Labour MEP Richard Corbett earlier called for MEPs to publish a regular breakdown of what they spend on staff and second homes like MPs will soon be forced to do.
Labour's group leader at Brussels, Gary Titley, also backed greater transparency - pointing out that Labour was the first British party to introduce independent auditing of MEPs expenses, a move followed by the Tories and Lib Dems.
But he said publishing full details - including receipts - would be a "distraction" and it would be better for the European Parliament to employ staff directly rather than individual MEPs.
'Incapable of reform'
The Lib Dems are also pushing for greater transparency, with North West England MEP Chris Davies calling earlier for a cross-party agreement to increase accountability.
He said all candidates for the European Parliament elections, from British parties, should be made to sign a code of conduct requiring them to meet high standards of financial probity.
But he warned that efforts to reform the European Parliament as a whole would probably end in failure.
He said: "The Giles Chichester affair has provoked another furore over MEP expenses in the UK, but there will not be a mention of it in the Italian, Greek or Romanian press.
"The European Parliament may be incapable of reforming itself.
"Dutch, Scandinavian and British campaigners will never secure a majority in favour of radical improvement while there is no pressure on others to vote for change."