Mark Warburton admits Rangers are lagging behind Celtic both on and off the pitch but says it would be wrong to rush through a rescue package.

The Ibrox boss has faced further questions over the club's direction in the wake of their 1-0 defeat to the Hoops in Sunday's BetFred Cup semi-final.

Former Gers manager Graeme Souness claims the Englishman has not had the backing he needs from chairman Dave King's board, and reckons it could take his old side five years to close the gap on their rivals.

Read more: Erik Sviatchenko: Rangers still haven't narrowed the gap to Celtic after League Cup semiGlasgow Times:

Warburton was in no mood to disagree with Souness but stressed there is no way the Light Blues faithful would stand for spending another half a decade in the Parkhead outfit's shadows.

However, given the club's recent financial woes, the former City trader also stressed that spending recklessly was not the answer.

Warburton said: "Football is a game of opinions and Graeme is a very knowledgeable football man, steeped in experience who knows all about Glasgow too. You have to respect his opinion.

"There is a financial gap that exists at this moment in time. That's clear for everybody to see.

"They (Celtic) have a squad packed with international players. They are in the Champions League this year and are getting all the benefit of that in terms of playing experience and financial income.

Read more: Erik Sviatchenko: Rangers still haven't narrowed the gap to Celtic after League Cup semi

"We recognise and respect that. We then have to sit down and decide how do we close it? How do we improve our squad? Can we invest astutely and wisely?

"We have to set aggressive targets to try and close the gap. If our supporters can see that we will be in a good place.

"I read some ludicrous comments this morning about how my City background should make me aware of the power of financial muscle. I'm not a rocket scientist but I'm not a fool.

"Of course you recognise the implications of a rival club with a strong financial base at this moment in time. The worst thing Rangers could do is spend recklessly to try to close that gap too quickly.

"We know the gap is there. But what is also important is the target setting so we know what we have to do in what time frame in what gap.

"The worst thing we could do is not build strong foundations here, and from the chairman and the board down the club is very clear what we have to do.

"I guess Graeme is acknowledging the gap with his experience. It has to be shorter period [than five years] in my opinion. I'm not ignoring Graeme's opinion but our job has to move quicker.

"Would the Rangers fans accept five years? I don't think so. I hope they know we're on a project and on a road. Hopefully we're making good progress down that road, but they need to see that progress."