Bayern Munich have signed Tottenham defender Eric Dier on loan until the end of the season with an option to make the move permanent, the clubs announced Thursday.

Bayern will pay a fee of between €2 million and €4m, depending on performances, to make the deal permanent, sources told ESPN.

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Bayern had been keen on signing Radu Drăgușin and tabled an offer to rival Spurs' bid totalling around €30m but the Genoa defender opted to move to north London, forcing the Bundesliga club to seek alternative options.

"We're pleased we've been able to sign Eric Dier," Bayern sporting director Christoph Freund said. "He's long been in our thinking for this transfer window. Eric will be a valuable part of our defence. His sporting abilities and international experience will help the team both on the pitch and in the changing room."

Dier is out of contract at Tottenham this summer and was deemed surplus to requirements by head coach Ange Postecoglou.

Eric Dier has fallen out of favour at Tottenham this season. Eric Alonso/Getty Images

"This move is a dream come true for me, because as a child you want to play for a club like Bayern one day," Dier said.

"Bayern is one of the biggest clubs in the world and has an incredible history. I want to help the team with my versatility in defence. I'm really looking forward to my new teammates and the fans at the Allianz Arena, which in my eyes is one of the best stadiums in the world."

Despite missing centre-backs Micky van de Ven and Cristian Romero for extended periods this season, Postecoglou preferred to use full-backs Ben Davies and Emerson Royal at the heart of his defence.

Consequently, Dier has started just one match this season -- 2-1 defeat at Wolves in November -- and made just four appearances across all competitions.

Davies suffered an injury in Spurs' 1-0 FA Cup third-round win over Burnley last Friday and when asked whether the club could still afford to lose Dier this month, Postecoglou replied: "Yes."

West Ham were among several other clubs monitoring Dier but terms were swiftly agreed with Bayern once they formalised their interest.

Dier joined Spurs from Sporting Lisbon in August 2014 for £4m and has made a total of 365 appearances for the club. He has also been capped 49 times by England.

Dier will join former Spurs teammate Harry Kane at the Allianz Arena after he made the same move to Munich last summer.