Rudi Voller has not taken Mario Basler's criticism of Bayer Leverkusen well. Simon Hofmann/Bongarts/Getty Images

Bayer Leverkusen sporting director Rudi Voller has called Mario Basler "a part-time clown," in response to comments by his former Germany international colleague suggesting that Leverkusen are already preparing for Europa League.

On Tuesday, Leverkusen were held to a goalless draw by Tottenham Hotspur keeper Hugo Lloris in front of a capacity crowd of 28,887 at the BayArena. It was Bayer's third draw in as many Champions League matches this season, leaving them third in group E, two points behind leaders Monaco and one behind Spurs.

"If I am totally honest: I just don't follow Leverkusen during the year," Basler said. "This club means nothing to me. Just look at the stadium. It's not sold out. It's a Champions League match, and a lot is at stake for Leverkusen."

Basler, a Germany international in the 1990s and known for being outspoken, went on to accuse the Leverkusen supporters of not being interested in their club's fate.

He said: "Maybe they are looking forward to playing Europa League. To me they are a club without emotion, without fans, without anything."

Questioned about Basler's remarks, Leverkusen sporting director Rudi Voller hit back at the former Bayern Munich and Bremen player.

"I feel sorry for Mario," he said. "I played alongside him at the 1994 World Cup, and I liked him back then, but he has turned into a part-time clown, and a bad one too."