By Bill Wilson BBC News business reporter at the Sports Law and Business forum

All eyes are on a potential stadium handover at the end of March

Executives at Wembley Stadium are confident of attracting the remaining businesses needed to fill its 14-slot sponsorship programme before the venue opens later this year.

On Monday, stadium builder Multiplex admitted there was only a 70% chance of Wembley being ready in time to host the FA Cup final on 13 May.

The showcase game of the English season is one of the major attractions being offered to potential sponsors as part of their Wembley Stadium package, but Multiplex UK managing director Martin Tidd has said there are "risks" in meeting the 31 March handover.

Sponsors will be buying into the values of excellence, passion, quality, heritage, atmosphere and integrity Darren Berman, Wembley

So far the stadium company has secured two big names for its four-strong Founding Members sponsorship tier, and another two firms to its second level ten-strong Official Suppliers tier.

That leaves a total of ten packages to be taken up. In the top section the beer and mobiles categories remain, and in the next tier the hotel, soft-drinks, cars, film, media, financial services, snack foods and confectionary categories are open.

'Series of events'

But, despite Monday's news, Darren Berman, head of legal and corporate affairs at Wembley National Stadium Limited, says the stadium company is "a long way down the road to completing our sponsorship programme".

Speaking to the BBC News website at the annual Sports Law and Business Forum, held by organisers C5 in London, he said the issues of the stadium opening and securing sponsors were not inextricably linked.

PLANNED WEMBLEY EVENTS England football internationals FA Cup final and semis Football League Cup final FA Charity Shield FA Vase, FA Trophy final Promotion play-offs Schoolboy internationals Rugby League final Music concerts

"All of the sponsors have been asking about potential late opening of the stadium," he said.

"But we are offering a package and series of events, sponsors are not being offered a set opening date."

He said that sponsors understood they were signing up for the long-term and not just a single event such as the cup final, with the sponsor package including around 30 potential events a year, and until July 2010.

Mr Berman said if the stadium was not open in time for the FA Cup Final it would "not be the end of the world".

The final, he said, will go to Cardiff, and the stadium will "be open for other major events".

Use of pitch

Mr Berman insisted that money from sponsors was not needed to complete building work at the new stadium, nor was it needed for to provide the backbone of revenues when the Wembley is up and running, with sponsorship accounting for less than 8% of income.

"It is nice to have them, but not essential in the time line towards opening," he added.

Microsoft was the first Founding Partner sponsor to sign up for Wembley

"However, everyone is still focussed on trying to get Wembley ready for the Cup Final".

So far, firms that have signed up in the Founding Members tier are Microsoft (technology) and Umbro (sportswear), and in the Official Suppliers tier Npower(power) and Betfred (betting) are on board.

He would not reveal the sum that Wembley is trying to raise from sponsorship, but it has been reported that Microsoft's deal was worth at least �5m.

Microsoft technology will be used in the stadium, and the firm will get use of the pitch for 90 minutes a year, as will the other three top-tier partners at the 90,000-seat venue.

'New partners soon'

Felicity Reeve, of law firm Bird & Bird, is an expert on the exploitation of sponsorship rights, and has been advising Wembley Stadium.

"We are confident of naming the remaining two Founding Partners in the next few weeks," she said. "We are quite close to making announcements on those."

We have made it clear to sponsors they are sponsoring the stadium, not the event Felicity Reeve, Bird & Bird

She said the concept of a restricted "family" of sponsors had been drawn up to provide a clearly marked-out programme that would "allow the only way for firms to directly associate themselves with the stadium".

The top tier sponsors will have a total of 170 plaques at strategic points around the stadium featuring their names.

All 14 sponsors will be able to use the Wembley brand on their material, and there will be ticket packages available too.

As well as the 30-odd sporting and music events at the stadium, the sponsors will also have their brands accessed by people attending the stadium for exhibitions, banquets, conferences, tours and visiting the stadium shop.

The Venue of Legends will soon be home to the England team again

However, sponsors have to be aware that if the stadium is being used to hold an event - such as the Champions League final - that has its own exclusive sponsors, then the Wembley signage and other sponsor opportunities may be restricted.

For example Uefa, Fifa, and the International Olympic Committee would demand a totally "clean" unbranded stadium.

"We have made it clear to sponsors they are sponsoring the stadium, not the event," insists Ms Reeve.

"But in most cases it will be looked at in a case-by-case way, and these will be worked through. Sponsors know at the outset that there may be a conflict."

'National heritage'

However, Mr Berman remains upbeat that companies will continue to snap up the opportunity to sponsor the stadium, not least because Wembley estimates 2.5 million people will pass through its doors a year.

There is, he says, also the kudos in being associated with the English national stadium which is home to the English national game - football.

"This is not just a building, it is part of the national heritage, it is an icon. It is somewhere people aspire to visit and is a unique property and brand.

"Sponsors will be buying into the values of excellence, passion, quality, heritage, atmosphere and integrity."