Assange, a former computer hacker now at the center of a global controversy after WikiLeaks released a trove of classified U.S. diplomatic cables at the weekend, denies the Swedish allegations.
The website of Interpol, the international police agency, said anyone with information on the Australian-born Assange, 39, should contact their national or local police.
Red notices allow arrest warrants issued by national police authorities to be circulated to other countries to facilitate arrests and help possible extradition.
Assange's current whereabouts are not known and he is believed to move from country to country.
A Swedish court on November 18 ordered the detention of Assange. The prosecutor's office had started an investigation into allegations of rape, sexual molestation and unlawful coercion against Assange in September.
Assange's lawyer, Bjorn Hurtig, told journalists after the hearings he expected a European arrest warrant would be issued for Assange, who had sometimes visited Sweden in the past, and that he would probably appeal.
Assange has called the allegations baseless and criticized what he has called a legal circus in Sweden, where he had been seeking to build a base in order to benefit from its strict journalist protection laws.
WikiLeaks has angered the United States by releasing more than 250,000 State Department cables exposing the inner workings of U.S. diplomacy, including brutally candid assessments of world leaders.
WikiLeaks had in October released nearly 400,000 classified U.S. files on the Iraq war, which Assange said showed 15,000 more Iraqi civilian deaths had occurred than thought.
Bank of America Corp's shares declined 3 percent on Tuesday amid investor fears the largest U.S. bank by assets may be at the center of WikiLeaks next document release.