Hoffenheim's former Liverpool forward Ryan Babel has again landed himself in hot water with football officials after another outburst on his Twitter account in Germany.
The 25-year-old is being investigated by the German Football Federation (DFB) after posting, "I don't know, I think the referee was on drugs," on his official Twitter account after being sent off on Saturday in the Bundesliga.
The Dutch winger was shown two yellow cards in Hoffenheim's 3-1 defeat at Hertha Berlin after a clash with the hosts' captain, Levan Kobiashvili, and made the remark about referee Thorsten Kinhoefer.
The DFB's disciplinary committee on Monday demanded a statement from Babel, who also got in trouble for a Twitter post while playing for Liverpool.
In January 2011, Babel was fined £10,000 ($16,000) after admitting a charge of improper conduct by the Football Association for posting a link to a mocked-up picture of English referee Howard Webb wearing a Manchester United shirt.
In addition to sending the link to his followers, Babel wrote: "And they call him one of the best referees. That's a joke," after Webb sent off Liverpool captain Steven Gerrard in a 1-0 FA Cup defeat against United.
Babel joined Hoffenheim from Liverpool later that month, but this latest episode will further strain relations with coach Markus Babbel, who dubbed the Dutchman's actions "stupid" after he was sent off in Berlin.