Nearly two dozen asylum seekers are among those suspected of involvement in mass assaults and muggings on New Year's Eve in Cologne, officials said on Friday, intensifying a debate about Germany's welcome for hundreds of thousands of migrants.

Some 121 women are reported to have been robbed, threatened or sexually molested by gangs of men of foreign descent as revelers partied near the city's twin-spired Gothic cathedral.

The assaults have shocked many Germans and led to calls for tougher laws to punish migrants who commit crimes. On Friday, Cologne police chief Wolfgang Albers, who had been heavily criticised for his handling of the violence and police communications afterwards, was dismissed.

Some 1.1 million migrants arrived in Germany last year, far more than in any other European country, most of them fleeing war or deprivation in the Middle East.

Chancellor Angela Merkel has resisted domestic pressure to introduce a formal cap on the numbers, repeating her "We can do this" mantra to Germans. But the Cologne attacks have deepened scepticism among the population.

Cologne police said on Friday that they had arrested two males aged 16 and 23 with "North African roots" suspected of involvement in the assaults.

SUSPECTS IDENTIFIED

Separately, German federal police said they had identified 32 people who were suspected of playing a role in the violence, 22 of whom were in the process of seeking asylum in Germany.

The federal police documented 76 criminal acts, most them involving some form of theft, and seven linked to sexual molestation.

Of the 32 suspects, nine were Algerian, eight Moroccan, five Iranian, and four Syrian. Three German citizens, an Iraqi, a Serb and a US citizen were also identified.

Interior Ministry spokesman Tobias Plate did not say if any of the suspects had been charged. "The investigations are ongoing," he said.

Federal police were on duty inside Cologne's main train station, while state police were deployed outside, near the cathedral, where most of the assaults appear to have taken place. So the numbers probably represent only a portion of the crimes that took place.

Amateur videos from the night show groups of young men jumping around chaotically, shooting fireworks into the crowd and pushing bystanders. A full police report on the evening is due in the coming days.

In response to the assaults, Merkel's conservative Christian Democrats (CDU) have called for tougher penalties against offending asylum-seekers.

A draft paper seen by Reuters ahead of a meeting of the party leadership in Mainz said migrants who have been sentenced to prison or probation should be ineligible for asylum.

"Why should German taxpayers pay to imprison foreign criminals?" said Vice Chancellor Sigmar Gabriel, leader of the Social Democrats (SPD), Merkel's coalition partner.

"The threat of having to spend time behind bars in their home country is far more of a deterrent than a prison sentence in Germany."

The CDU paper calls for lower barriers to the deportation of criminal asylum seekers, increased video surveillance, and the creation of a new criminal offense of physical assault.

The attacks have raised doubts over whether Germany, which has a large Turkish Muslim community dating from an influx of workers in the 1960s and 70s, can successfully integrate the latest wave despite Merkel's attempts at reassurance.

"There are many refugees that are happy to have survived, to have made it here, and who are looking for jobs. These people who can contribute to our country are welcome," Peter Tauber, general secretary of Merkel's party, told Deutschlandfunk radio.

"But clearly there are also some who haven't understood what kind of opportunity they've been given."

Julia Kloeckner, leader of the CDU in the state of Rhineland-Palatinate and seen as a possible successor to Merkel, told ZDF television the attacks had been a wake-up call for Germany.

"I think we really need to take off the blinkers," she said.-Reuters