Borussia Dortmund sporting director Ole Book insists it would take "astronomical sums" for the club to consider selling Felix Nmecha this summer.

Nmecha enjoyed a strong campaign for Dortmund last season, while his profile was further boosted by some impressive displays at this summer's World Cup for Germany.

The 25-year-old scored the opening goal in their 7-1 rout over Curacao before assisting the winner against Ivory Coast, which clinched Germany's place in the knockout rounds.

Germany suffered a surprise last-32 exit at the hands of Paraguay, but Nmecha was hailed as one of their few strong performers at the tournament. 

For Dortmund, Nmecha scored six goals and provided three assists in 47 appearances last season, which was his third campaign at the club.

Among Dortmund midfielders, Nmecha led the way for successful passes (1,390) and duels won (162), while only Jobe Bellingham (47) recorded more interceptions than his 37.

Reports emerged over the past few days suggesting Newcastle United were interested in signing Nmecha to replace Bruno Guimaraes, who is set to join Arsenal.

Manchester United have also been linked with the midfielder, though Dortmund reportedly want €120m for his services.

"I would consider a transfer extremely unlikely," Book told Ruhr Nachrichten.

"Of course, astronomical sums can theoretically always be involved, but I can pretty much rule that out for Felix Nmecha this summer."

Nmecha joined Dortmund's pre-season camp in Japan last week, featuring in their 1-0 win over Tokyo FC.

They have two more friendlies remaining, against Arsenal and Roma, before the Franz Beckenbauer Supercup on August 22, when they face Bayern Munich.