"She has applied for pardon. A case is being prepared by the ministry," justice ministry legal advisor Lars Brandt told AFP.
"The government will make the final decision," Brandt added.
The procedure would take some two months.
In a letter to the justice ministry, a copy of which was obtained by AFP, Plavsic, 76, said her advanced age, failing health and poor prison conditions meant her sentence was "much, much longer" than her 11-year penalty.
Her letter was dated November 27, but the Swedish translation only arrived at the ministry on January 15.
In September 2006 Bosnia's ambassador to the United Nations, Milos Prica, acting in a private capacity, requested Plavsic's release, Brandt said.
Plavsic said in her letter that she first learned of Prica's request through Swedish media in October.
The International Criminal Tribunal for the former Yugoslavia (ICTY) in The Hague sentenced Plavsic in February 2003 after she admitted playing a leading role in the campaign of persecution against Bosnian Croats and Muslims during the country's 1992-95 war, which claimed more than 200,000 lives.
She is the highest ranking official of the former Yugoslavia to have acknowledged responsibility for the atrocities committed in the Balkan wars.
Sweden agreed to house Plavsic in one of its prisons in response to a request from the tribunal.
She was transferred to Sweden in June 2003 and is an inmate at the Hinseberg women's prison.