Unite’s controversial £98m hotel and conference centre could face an independent QC-led review if any evidence of misspending is found, the favourite in the race to replace Len McCluskey has declared.

In a wide-ranging interview with HuffPost UK, assistant general secretary Steve Turner said that he was prepared to order a probe if there was any evidence of anything “untoward” over the handling of the project in Birmingham.

The new building complex, which will house the union’s regional headquarters as well as a four-star, 170 bed Aloft hotel and 1,000-seat conference centre, has been dogged by criticism as its costs soared by £40m.

The union has insisted the extra costs were caused by high standards of unionised labour, the need to strip cladding related to Grenfell changes and the addition of an extra floor onto the hotel.

Turner, who is in pole position to succeed McCluskey because of his endorsement by the traditionally dominant United Left grouping in the union, defended the “world class” building project and stressed it was an asset.

But he said that if he became general secretary he would overhaul the union’s financial processes and if there was any suggestion of unexplained spending he would order a review.

“If I felt that there was anything untoward or if there was evidence suggesting that there was anything untoward – and I haven’t seen any of that genuinely, I’ve not seen anything – if there was, then absolutely I would have an independent investigation into it because this is our members money.

“If I was genuinely concerned, then absolutely I would have an independent QC review. But I’ve been to Birmingham, I’ve had a look around the centre and it is a world class, fantastic facility. It will be picked up by others who want to use it for conferences, whether in the business world or in the trade union world.

“I think that will be a revenue earner. We’re not in negative equity, it’s already valued at well over 100 million quid. So my issue with it is not the build itself. My issue with it really is about due diligence and oversight.”

Turner said transparency for union members was among his concerns.

“We’re all as guilty as anybody else because we’ve all been in the executive [council] meetings where things have been raised and the cost implications have not perhaps been discussed in the way in which they should have been discussed.

“I think always in our movement, there’s an element of trust, and in the space between [when] that decision was taken and when the news was finally broken, that facility has cost us 98 million quid, there should have been a whole series of stages on that journey, that made sure that our members knew what we were doing, and what was happening, at every level of our union.

“It shouldn’t have been a surprise leaked to the press that Unite spent 98 million quid on a centre.”

Turner added that he would amend the union’s financial scrutiny. “The question for me is, is that oversight question, by our executive, by our finance and general purposes committee.

“So I would put measures in place on [my] election, I will put training in on their responsibilities, and their duties. They’re not there just to meet once every three months for a few days just to rubber stamp.

“I think the tendering process should have been more transparent and more open. And I would change the rules around that so that in future all of this was done.”

Gerard Coyne, who narrowly lost to McCluskey in 2017’s Unite general secretary election and is again running for the top job, has made the hotel complex a central plank of his campaign to shake up the union.

In an open letter to Unite members, he has questioned whether the £98m was spent “wisely” or “properly”.

When contacted by HuffPost UK, Unite reissued a statement it put out earlier this month: “Every step of the way, the production of this complex was overseen by independent surveyors and architects.

“Accountability was built into the process to ensure that at every stage of this development we got value for this union’s money.

“All this was overseen by our democratically-elected, independent 62-strong executive council. This is the body elected by our members to keep this union properly run and accountable, and they do this superbly.”

Other candidates declared in the contest to succeed McCluskey include assistant general secretary Howard Beckett and national organiser Sharon Graham.

In his interview, Turner also warned that a split Left vote could allow Coyne to win the election.