Arsenal are in advanced talks with Brighton over the signing of defender Ben White.
Sky Sports News reported Arsenal had a £40m bid rejected last week and discussions are continuing over a deal that could be worth in excess of £50m.
Brighton have not made public their asking price but club owner Tony Bloom will not stand in White's way if he wants to leave - provided that valuation is met.
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Negotiations are centred on the structure of payments and personal terms are not expected to be a problem, as all parties are hopeful a deal can be completed.
There remains a gap in the valuation and a difference in how the deal would be structured, with Brighton under no pressure to sell.
White, who is predominantly a centre-back but can also provide cover in midfield, made 36 Premier League appearances for Brighton last season after spending the 2019/20 season on loan at Leeds.
He impressed as Brighton survived relegation and finished 16th in the Premier League with the joint-best defence in the bottom half of the league as they conceded 46 goals.
White earned his first England call-up in May when he was named in Gareth Southgate's provisional 33-man squad for Euro 2020 and made his full international debut in a warm-up match against Austria.
He was originally left out of Southgate's 26-man squad, but later replaced the injured Liverpool right-back Trent Alexander-Arnold after he suffered a thigh problem against Austria.
Meanwhile, Arsenal remain in talks with Roma over the sale of Swiss midfielder Granit Xhaka.
There is still a small gap in valuation, but all parties are confident a resolution will be found, with any deal likely to be finalised after Xhaka's participation in the Euros with Switzerland.
Matteo Guendouzi could be another player set to leave Arsenal in the near future, as Marseille continue talks over a potential move for the midfielder and Benfica remain interested.
Guendouzi was on loan at Hertha Berlin last season and is not in Mikel Arteta's long term plans. Arsenal prefer a permanent transfer, or a loan with an obligation to buy at the very least.
Arsenal are also in positive talks with Anderlecht over the signing of midfielder Albert Sambi Lokonga.
A fee for the Belgium U21 international is yet to be agreed but the two sides are not far apart in valuation, with personal terms not expected to be an issue.
What is knock-on effect of White deal?
Sky Sports News reporter Dharmesh Sheth:
"This is big news for Arsenal. You will remember that last week we reported that they had a bid of around £40m rejected by Brighton for White, but they've had further discussions and negotiations are continuing. They're at a very positive stage I'm told over a deal that could be worth in excess of £50m.
"The negotiations are centred on the structure of the payments but personal terms are not thought to be a problem and I've been told that all parties are 'cautiously optimistic' that a deal can de done.
"A couple of players at Arsenal could be affected. Konstantinos Mavropanos, who has been on loan for the past couple of seasons, is close to a loan move back to Stuttgart with an obligation to buy depending on certain conditions - basically their performance over the course of next season.
"The other player it could impact is William Saliba, who joined Arsenal from St Etienne in the summer of 2019. He went straight back on loan for a season and then spent last season on loan at Nice. He's someone who was signed before Mikel Arteta arrived at the club, under the guidance of Unai Emery and Raul Sanllehi.
"My information is that by the time pre-season re-starts, Saliba will have had talks with the Arsenal hierarchy to discuss whether it's best to remain at the club next season, to go out on loan or to move permanently out of Arsenal. If White joins, there will be quite a lot of players in front of him so there will be discussions over how to best serve the player. He could move down the pecking order."
White, Ramsdale interest suggests defensive priority for Arsenal
Sky Sports' Nick Wright:
"Arsenal had the third-best defensive record in the Premier League last season, conceding just 39 goals across their 38 fixtures, but their interest in White and Sheffield United goalkeeper Aaron Ramsdale suggests Mikel Arteta regards defensive improvement as a priority this summer.
"The Gunners do look light at centre-back following David Luiz's departure. William Saliba is due to return from his loan spell with Nice ahead of the new campaign and will hope to compete for a place in the side but Arteta evidently feels an external solution is required.
"White impressed for Brighton during his first season in the top flight, starting all but two of their Premier League fixtures and at times featuring in central midfield. The 23-year-old's performances earned him a place in England's Euro 2020 squad.
"White's ball-playing ability and age make him an enticing proposition for Arsenal and they doubtless see similar qualities in Ramsdale.
"The goalkeeper, also 23 and also called up to the England squad this week, showed his potential during a difficult season with Sheffield United and is comfortable playing out from the back.
"Arsenal's interest in Ramsdale may cast doubt on Bernd Leno's future. Together with the club's pursuit of White, it also shows Arteta wants a defensive refresh as a priority."
Arsenal will start their 2021/22 Premier League campaign away at newcomers Brentford on Friday August 13, live on Sky Sports.
Mikel Arteta's side, who finished a disappointing eighth in the Premier League table, then have a London derby at the Emirates against European champions Chelsea on August 21, before going to current champions Manchester City on August 28.
Arsenal's first north London derby comes on the weekend of September 25 at home to Tottenham, while the return fixture will be on the weekend of January 15 at the Tottenham Hotspur Stadium.