The parliament of Sweden on Wednesday passed a bill stating that sex without consent constitutes rape, even when there are no threats or force involved, in a move welcomed by rights groups including Amnesty International.

The law was approved after a 257 to 38 vote.

The law amends previous legislation that said it was necessary to prove that a perpetrator used force, threats or that a victim was in a vulnerable situation, for instance being drunk, to secure a rape conviction.

The new law enters into force on July 1, and states that a person must consent to sexual activity with words or body language.

Tomas Tobe, justice affairs spokesman for the opposition conservatives, said his party had voted in favor of the law despite some doubts.

One concern was that there would be "too strong a focus" on the victim, he said, for instance on whether or not they had clearly communicated that they were willing to engage in sexual activity.

However, Tobe told Swedish radio after the vote that the new law could help change attitudes.

"This is a big feminist victory," said Annika Hirvonen Falk of the Greens, a partner in Sweden's red-green government.

Anna Blus, women's rights researcher for Europe with Amnesty International in London, said: "This change in law will make Sweden only the 10th country in Europe to recognize that sex without consent is rape."

She added: "Most European countries still define rape based on physical force, threat or coercion, and these outdated definitions have caused immeasurable harm."

The Swedish government presented the bill in spite of the fact that the advisory Council on Legislation, which studies draft bills, had said existing legislation was sufficient.