Louise Frevert, a member of the Danish People's Party and a member of parliament, a key supporter of the minority governing coalition, later claimed the articles had been posted on the site by a party colleague without her knowledge.
The postings prompted widespread outrage in Denmark.
The text, which was withdrawn last week, said some young Muslims believe it is their right to rape and assault native Danes.
"What has been reproduced is an unacceptable attitude," Prime Minister Anders Fogh Rasmussen said.
Police said on Monday that they were investigating whether Frevert, who plans to run for the job as Copenhagen's mayor in November, could be charged with violating Denmark racism law.
Also on Monday, Danish media published excerpts from a 2004 political pamphlet by Frevert that contains passages claiming Muslims have "secret" plans to take over Denmark.
Tanwir Ahmad, a Muslim member of the Copenhagen city council, accused Frevert and the anti-immigration Danish
People's Party of scaremongering and spreading falsehoods about his religion.
"The only plan we have is to be accepted as equal citizens in this country," Ahmad said.
Frevert's name was on the cover of the booklet, but she said parts of it had been written by her website administrator.
On Saturday, the administrator, Ebbe Talleruphuus, took the blame for posting articles on Frevert's internet site without her permission. He also resigned as her webmaster and quit the party.