Berlin, Germany - As Germany celebrated the twentieth anniversary of the fall of the Berlin wall, a free music concert staged by Irish rock-band U2 drew controversy as a section of the capital had to be walled in to separate the crowd from the rest of the city.

For those old enough to remember, the temporary barrier reignited memories of the panic surrounding the sudden erection of the old wall in August 1961.

One of those who were trapped said today: "I had just sat down, next to what looked like a makeshift bandstand. I turned around and suddenly I saw a huge barbed wire cordon going up. Some were trying to make it over to the other side. I turned back around and my worst nightmare was confirmed: U2 were performing and there was no way out."

As the concert continued, thousands could be seen inside the zone trying to escape by climbing the gates and throwing themselves against the razor wire fence.

Families were eventually reunited with teary-eyed loved ones who had managed to become stranded inside the restricted zone overnight.

"It was absolute hell," one man said, continuing: "we thought it couldn't get any worse, but then Jay-Z came on. This was advertised to us all as a free concert; a social paradise for everyone."

"But I guess you really do get what you pay for."