A memorial service has been held in the German city of Duisburg to remember victims of last week’s Love Parade tragedy.

Twenty-one people died and more than 500 were injured last Saturday when panic broke out in an over-crowded tunnel, the only access point to the techno festival.

The memorial service was held at the Salvator Church in Duisburg and was joined by friends and relatives of those killed in the tragedy, as well as President Christian Wulff and Chancellor Angela Merkel, who cut short her holiday to attend.

The church holds around 600 people, but many more watched on large screens put up in other churches and at Duisburg’s football stadium, where a large black cross was erected on the pitch.

The Mayor of Duisburg, Adolf Sauerland, did not attend the memorial service, saying he feared his presence may hurt the feelings of relatives of the victims, according to the BBC.

He remains under police protection after receiving death threats. Many people hold him responsible after warnings about the inadequate size of the venue went unheeded. Earlier in the week he was chased away by angry mourners from a vigil being held near the foot tunnel in honour of the victims and there have been calls for his resignation.

Flags are flying at half mast across Germany today as a mark of respect for the victims, who were aged between 18 and 40, and came from several countries, including Spain, Italy and China. Fourteen Germans were among the dead.

A march is due to take place this afternoon from the Duisburg train station to the scene of the disaster, where flowers, candles and photos have been left by shocked mourners.

Police are continuing their investigation into the disaster but have blamed Love Parade organisers for failing to manage the large crowd, which numbered in the hundreds of thousands.

Earlier in the week, the head of the Evangelical Church in Germany, Bishop Nikolaus Schneider, said God was with the victims.

“Amid the horror and the questions, there is one thing I am sure of: God never left those who feared and fought for their lives in the panic,” he wrote in local newspaper, the Rheinischen Post.

He said God was “with those who lost their lives” and those now in mourning, but added that God would also not leave those “who made mistakes” in planning the event.

He stressed that the tragedy should not be seen as God “pointing the finger” at the Love Parade or its organisers.

“And I absolutely cannot interpret the deaths as godly punishment for those taking part,” he concluded.