Protests against potential outside investment in German football escalated on Friday with incidents halting games in Dortmund and Hamburg. Borussia Dortmund’s 3-0 home win over Freiburg was stopped for a period in each half after home fans threw tennis balls and foil-wrapped chocolate coins on to the pitch at Signal Iduna Park. Donyell Malen put the hosts in front in the 16th minute, before the first protest caused a 10-minute delay with the Dortmund midfielder Emre Can speaking to fans in an attempt to curb the protests. After play resumed, Malen got his second from Niclas Füllkrug’s pass in first-half stoppage time, and Füllkrug headed the third late on. There were more extreme measures taken in the second division as Hamburg’s home game against Hannover was repeatedly interrupted. A group of Hamburg fans reportedly attached bicycle locks to a goal during the half-time interval, causing a 30-minute delay as Volksparkstadion ground staff worked to remove them. Hannover fans, meanwhile, displayed a banner showing the face of the club president Martin Kind in crosshairs. They also held up signs protesting against CVC and Blackstone, the two prospective buyers in the league’s investment deal. The referee took both sets of players off after the banners were unfurled, and a warning that the game could be abandoned was displayed on screens at the ground. Hamburg were 3-1 down at half-time and fought back to level at 3-3, only to concede again in the 98th minute, either side of two late red cards for the hosts. Hannover held on to win 4-3, with the game finishing more than two hours and 40 minutes after it had kicked off. There have been regular protests since last year against a plan to sell a stake in marketing revenues to a private equity investor for an up-front payment. As the league moves closer to an agreement, fans are becoming more disruptive. Kind has attracted controversy over his role in the December vote to proceed with the investment talks. The proposal passed with approval from 24 of the 36 clubs in the top two men’s divisions, the exact two-thirds majority needed. The 79-year-old businessman has long been involved with Hannover, but has refused to say how he voted on the proposal, while the Hannover members’ club has said it asked him to vote against.