Union Berlin have accused Borussia Dortmund of "amateurish and chaotic organisation" after thousands of supporters were forced through a small, fenced-off area before Wednesday's DFB Pokal clash, with one visiting fan telling ESPN FC: "I feared I would not get out of there."

The match at the Westfalenstadion, which Dortmund ultimately won after a penalty shootout, had to be delayed by 15 minutes as a result of the scenes outside the stadium.

Prior to the match, a report in the Berlin media said visiting fans "were planning an unparalleled pyro inferno" and were intending to bring flares and other fireworks worth around €2,500 to the stadium.

The report, and the vast number of away fans planning to travel, contributed to the local authorities' decision to label the match "high risk."

Danke an alle, die mitgereist sind & geduldig vor dem Stadion ausgeharrt haben #fcunion #dfbpokal https://t.co/0WnTHTlC1N pic.twitter.com/JGyAkIxQV2 - 1. FC Union Berlin (@fcunion) October 27, 2016

Over 10,000 Union fans ultimately travelled to Dortmund for the match, and BVB stepped up security, installing a secluded, fenced-off area in front of the away entrance where fans were searched individually, and which could only be entered through turnstiles.

Dortmund said on Twitter that 50 minutes prior to the original kickoff time, Union fans had tried to force their way into the ground, prompting the police to take action.

However, Union said in a statement that, when kickoff was nearing and thousands of fans were still waiting to get into the stadium, one of the fences fell to the ground and, with pressure mounting from behind, supporters were pushed into the secluded area.

"An amateurish and chaotic organisation on-site led to significant disruption for thousands of away fans," Union Berlin said in the statement on Thursday evening, adding that the size of the secluded area and the speed of the security checks were "completely unsuited" to the number of fans in attendance.

"There was no organised or deliberate breakthrough by Union fans. Moreover, a lot of people were put at risk by organisational weaknesses," the club added.

Local police in Dortmund also confirmed to Sport1 that there was no breakthrough attempt by the away fans, but rather a "crowd outside the stadium entrance because things weren't moving."

Union fan Karsten Fuhrken told ESPN FC he feared he "would not get out of there" and added that people had fallen to the ground. He said security abandoned the area and police reacted by using pepper spray, which left 15 injured, according to a police report.

Union Berlin fans light flares in the away end at the Westfalenstadion, which caused the second half to be delayed. Leon Kuegeler/Anadolu Agency/Getty Images

In March this year, 17 Tottenham supporters suffered minor injuries ahead of the Europa League match at Dortmund. Police said at the time that their late arrival at the ground "led to an exertion of pressure on the gates," which resulted in "some 80 supporters" entering the stadium "uncontrolled." After a temporarily closure of the gates, there were "conflicts between visiting fans and security."

Martin Cloake, co-chair of the Tottenham Hotspur Supporters' Trust, told ESPN FC at that time: "The chaos at the entrance to the ground was unacceptable and avoidable."

Borussia Dortmund, who are preparing for another "high risk" match when they face local rivals Schalke on Saturday evening, have yet to issue an official response to Wednesday's incidents.

Earlier on Wednesday, meanwhile, five police officers suffered blast injuries when Union Berlin fans threw a banger at them at Dortmund's main station.

Kickoff for the second half was also delayed as Union supporters lit flares in the away end. The capital club did not comment on those incidents, but Dortmund police confirmed to ESPN FC that some pyrotechnics were found during the searches in the secluded area.