Shadow chancellor Michael Portillo has attempted to end days of speculation over Tory economic policy by pledging to stand by the party's controversial "tax guarantee".

Mr Portillo issued a statement on Thursday saying: "The Conservative party's tax guarantee stands.

"William Hague and I have both made it clear, and William reiterated it in the House of Commons yesterday, that the Conservatives will pledge to reduce the tax burden over the lifetime of the next Parliament."

The statement comes after speculation that the policy - which Labour says means the Tories would cut spending on schools and hospitals - was going to be watered down.

Last weekend, Mr Portillo said he was "ready to discuss" the tax guarantee, while Conservative leader Mr Hague subsequently called it an "aspiration" rather than a cast iron pledge.

The comments fuelled speculation that Mr Portillo had made a deal with Mr Hague to take full control over economic policy before his surprise promotion to the shadow cabinet earlier this month.

The shadow chancellor announced two U-turns - on Bank of England independence and the minimum wage - within days of taking on the role.

Sacking threat

But Mr Hague said on Thursday: "There was no deal beforehand or afterwards. I'm delighted he has accepted that, he has already made an extremely strong start to that job."

Meanwhile, the Tory leader warned Conservative Central Office staff who brief journalists against members of the shadow cabinet that they will be sacked.

The warning comes after reports that some staff at the party's London headquarters were suspected of acting on behalf of Mr Portillo at the expense of other senior Conservatives.

Asked about the situation, Mr Hague said: "I've got a full grip on it. I can tell you now what has been made clear is that anybody who briefs against anybody in the shadow cabinet won't be working for the party.

"That's very straightforward, I think it's very good. The party chairman should make that clear, as he has done so."

There have been reports that some workers at Tory Central Office want Mr Portillo - widely believed to hope to one day lead the Tories - as Conservative leader.

'Work together extremely well'

Mr Hague told BBC Radio 4's Today programme that his shadow chancellor backed the sacking threat.

"We work together extremely well and we expect everyone else to work together extremely well - and that's what's going to happen."

John Redwood, who was sacked from the shadow cabinet in last's reshuffle, told BBC Radio 4's The World at One: "A few people have clearly been putting unhelpful stories for William and the party in the newspapers.

"They are misleading and unhelpful and the sooner it is stopped the better."

Mr Portillo also announced that former Treasury official and diplomat Paul Raynes has been appointed as his private secretary.