Church and charity leaders today warned against tarnishing asylum seekers with accusations of terrorism after there were mixed reports in Germany about the identity of the attacker who targeted a Christmas market in Berlin last night.

According to reports based on leaked accounts from the authorities in Germany, a 23-year-old asylum seeker of Pakistani origin named Naved B was arrested over the lorry attack which killed twelve people and injured many more.

But tonight the picture was unclear as subsequent reports suggested that police were holding the wrong man – who denied the charges – amid claims that the attacker could still be at large.

When it appeared that the attacker was an asylum seeker, Bishop Paul McAleenan, the auxiliary Bishop of Westminster with responsibility for issues relating to asylum and migration, told Christian Today: "What has happened in Berlin defies comprehension. All people of goodwill are shocked, saddened and appalled by this attack. My thoughts and prayers and those of the whole Catholic community of England and Wales are with those affected in any way, and with the people of Germany who have been so generous to refugees. We must keep in mind that this attack is not representative nor a reflection of those who have sought sanctuary within our borders."

Russell Rook, who runs the Good Faith Partnership and is the founder of the Church Response For Refugees which works with the government in helping to house refugees across the UK, also told Christian Today: "Last week I heard how the father of a recently arrived family of refugees immediately began volunteering for a homeless charity, using his skills to provide warm and nutritious food for some of the most disadvantaged people in one of our largest cities. There are hundreds of stories like this that never see the light of day in the mainstream press and broadcast media.

"While last night's events in Berlin are ghastly beyond measure they are an horrific exception to an otherwise positive rule. Refugees contribute greatly to our communities economically, socially and culturally. As a country we should do all we can to welcome them and as the church we should remember that it is the welcome we show to the orphan, widow, stranger and refugee that qualifies us to be called God's people."

Meanwhile Cardinal Reinhard Marx, the President of the German Bishops' Conference, expressed his compassion for the victims and called for unity after the attack.

"The news from Berlin have deeply shocked me. The violence on the Christmas market is the opposite of what visitors were seeking," he said. "My compassion goes to the relatives of the dead and injured. For all of them I will pray. In these difficult hours for the city of Berlin and for our country, it is important for us to hold together and stand united as society."

Tonight there will be a vigil for the victims of the attack at 6pm local time at the memorial church near the scene of the outrage.

Earlier, the German Chancellor Angela Merkel said: "Twelve people, who were looking forward to Christmas and had plans for the festive season, are no longer among us...The whole of the country is with you in deep sadness...many pray for you."

Although Christmas markets have remained closed today in Berlin, they have stayed open across the rest of Germany.

Elsewhere, Italy is strengthening security measures for areas where crowds are expected for Christmas ceremonies, such as Pope Francis' appearance in St Peter's Square.

Interior Minister Marco Minniti led a meeting today of the heads of Italy's police and intelligence forces to review security after the truck attack.

An interior ministry statement does not specify the places where security will be tightened, but security officials in the past have said that extremists have noted that the Vatican, as a symbol of Christianity, is a target.