A police source told Reuters news agency: "Nobody has seen them. Their families are calling them, but nobody can reach them."
A 20-year-old woman using the name Sabrin al-Janabi last month said she was raped by three police officers after being detained during a search of her house.
The government denied her claims and cleared the officers after producing medical records it said showed she was not raped.
Hoda Abdel Hamid said: "Following the allegations of rape, several Sunni groups warned they would begin a revenge campaign ... they warned that there would be a huge wave of retaliation and this could be the beginning of it."
The Islamic State of Iraq said in its statement posted on a website on Friday: "This blessed operation is a response to crimes carried out by those infidels in their fight against the Sunnis.
"The latest of the crimes committed by these traitors was to rape our sister in religion."
|An internet statement said the abduction |
was retaliation for an alleged rape
The internet statement, which could not be independently verified, demanded that the "officers that participated in the horrible act" be turned over to them" and that "all Sunni Muslims held in interior ministry prisons be released".
It gave the government 24 hours to comply with its its demands and said the hostages would be killed if it did not.
The Iraqi Islamic Party, the country's largest Sunni group, has claimed that the alleged rape victim was a Shia and said it was investigating the case.
It is not known whether the accused police officers were Sunni or Shia.
Also on Friday, two car bombs killed at least 11 people in separate attacks across Baghdad.
The largest blast occurred at a used car lot near Sadr City, a Shia stronghold, killing 10 people, wounding 17 and setting several cars ablaze, police said.
The other blast was near a police patrol in southwest Baghdad, killing a policeman and wounding two civilians, police reported.