Crystal Palace have completed the signing of Jairo Riedewald from Ajax for €9m (£7.9m), reuniting the Dutch international with his former manager in Amsterdam, Frank de Boer.

The player’s arrival will be confirmed on Tuesday by the London club before he flies to Hong Kong to join his new team-mates.

Riedewald can operate at centre-half, left-back or in defensive midfield and was handed his Ajax debut by De Boer in 2013. The 20-year-old has been capped three times and joins Ruben Loftus-Cheek, who has moved across the capital on a season‑long loan from Chelsea, as a new arrival at Selhurst Park this summer.

Further reinforcements are to follow with Palace, whose squad arrived on Monday in Hong Kong to compete in the Premier League trophy, having spoken to Porto over a move for Bruno Martins Indi.

However, Stoke City, with whom Martins Indi impressed last season on loan, will compete strongly for his signature and could yet be joined by West Bromwich Albion and West Ham United in pursuit of the 25-year-old Dutch defender. The player is with the Portuguese club on their pre-season tour of Mexico.

Palace, meanwhile, are one of a number of clubs exploring the possibility of taking the Arsenal defender Calum Chambers on loan for the season, potentially with a view to a permanent deal.

De Boer will seek to add a goalkeeper to his ranks having sanctioned Steve Mandanda’s return to Marseille last week, though a move for Barcelona’s Jasper Cillessen may prove overly complicated to complete. Palace are also seeking to add greater attacking depth with a backup for Christian Benteke a priority while Connor Wickham continues his rehabilitation from cruciate knee ligament damage.

Assombalonga joins Middlesbrough from Forest

Middlesbrough have announced a club record deal to sign Britt Assombalonga from Nottingham Forest.

The 24-year-old striker has joined Garry Monk’s Championship side despite an injury-hit three years at the City Ground. The fee is believed to be in the region of £14m.

Assombalonga is a proven goalscorer in the Championship, having scored 30 times in 47 league starts since signing for £5.5m in 2014. However, persistent injuries have held back his progress, with a serious knee injury ruling him out for much of the 2015-16 season, but he signed a new five-year deal last summer after proving his fitness.

Boro have been looking to strengthen their attacking options after managing only 27 goals in the Premier League last season and claimed they beat off competition from top-tier clubs to sign the striker.

“I can’t wait to meet the manager and get ready for next season. There’s a good feeling around the place. From the minute I walked in it felt right,” Assombalonga said. “I want to thank the Forest fans for being behind me, especially after my injury.

“They gave me a chance in the Championship and I want to say thanks to them and wish them all the best for the season.”

A Forest spokesman said on the club’s website: “Middlesbrough outbid various other clubs to sign Britt Assombalonga. As a club we felt that since the fee agreed met the buyout clause in his contract and he wanted to move it would be wrong to stand in his way.” PA