German authorities revealed that they do not know the whereabouts of 130,000 people that entered their country last year, according to a parliament document viewed by AFP on Friday.

Out of the 1.1 million asylum seekers that flowed through German borders in 2015, "about 13 percent did not turn up at the reception centers to which they had been directed," the government said in a written reply to a lawmaker’s question.

Some of the refugees may have returned to their home countries, have gone on to another country, or went underground, the document said, in addition to the possibility of some repeated registrations of individuals, AFP reports.

A spate of New Year's Eve thefts and assaults on women in the city of Cologne, blamed largely on foreigners, caused public uproar. More than 1,000 criminal complaints were filed, more than 400 of those alleging sexual crimes. Two men were convicted of theft and given suspended sentences Wednesday in the first trials linked to those crimes.

New measures approved by parliament Thursday aim to address the issue of tracking asylum seekers by including plans to issue an identity document upon the arrival of a refugee and store personal data under a common database, an interior ministry spokesman said.

The German government is also moving to make it easier to deport foreign criminals. The changes would mean that even a suspended prison sentence would be grounds for deportation if someone is found guilty of certain crimes -- including bodily harm, sexual assault, violent theft or serial shoplifting.

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The Associated Press contributed to this report.