Sexist remarks and wolf-whistles could become criminal offences

Salacious whistles and sexist comments may fall foul of new laws against sexual harassment to which Britain is signing up, the prime minister will announce on Thursday.

The pledge to criminalise "verbal, non-verbal or physical" sexual harassment is one of the commitments in the Council of Europe's convention on violence against women, which David Cameron will commit to signing at a special event to mark International Women's Day.

Among the pledges in the convention, which has already been signed by 18 countries including Germany, France and Ukraine, is one to pass legislation or other measures to criminalise or impose other sanctions for "unwanted verbal, non-verbal or physical conduct of a sexual nature with the purpose or effect of violating the dignity of a person, in particular when creating an intimidating, hostile, degrading, humiliating or offensive environment".

Another clause would outlaw "psychological violence" – defined as "seriously impairing a person's psychological integrity through coercion or threats", language which suggests serious bullying could be covered by new laws.

Other measures Britain and other signatories would have to enshrine in law include compensation for victims of domestic violence; easy annulment or dissolution of forced marriages; and punishments for carrying out or coercing somebody into genital mutilation, forced abortions or forced sterilisation.

In a separate move, Cameron is expected to back government support for new laws to criminalise stalking, with jail terms of up to five years and unlimited fines.

Signing up to the European convention will be announced in a joint statement by Cameron and deputy prime minister, Nick Clegg, to mark International Women's Day. "The agreement is not just a piece of paper," says the statement. "It's going to lift the standards of protection for women across Europe, give greater support for victims and – crucially – bring many more perpetrators to justice."

Former attorney general Baroness Scotland, who worked on the convention for four years under the Labour government, said the clause on sexual harassment was not intended to cover less serious incidents such as wolf-whistling and public teasing. However, campaigners on the issue said the convention was "what we've been trying to get for years".

Julia Gray, founder of the London branch of US movement Hollaback, dedicated to getting rid of street harassment, said: "The way we see it is if you want to tackle it you tackle all of it – you say no to all forms of unwanted sexual harassment; that includes wolf-whistling, comments, everything."

A Downing Street spokesman said it was too early to discuss possible sanctions for sexual harassment.

Overall, the convention was largely modelled on UK laws and practices, but signing it would help protect Britain's high standards, said Scotland. "I praise God they have finally signed it, but I'm shocked they didn't sign immediately [in 2011]."

The announcement on stalking follows a year-long campaign for reform organised by the charity Protection Against Stalking and Napo, the probation and family court union.

The Conservative Lord Oliver Henley will table amendments on stalking law reform to the protection of freedoms bill in parliament. He will be followed by an official announcement from the prime minister at an evening reception to mark International Women's Day at Number 10.

In a statement released (WED) on Wednesday night, Cameron said: "Stalking is an abhorrent crime. It makes life a living hell for the victims – breaking up relationships, forcing the victims to move house, making them feel they are being watched 24 hours of the day. That is why we are explicitly criminalising stalking, to make sure that justice is done, protect the victims and show beyond doubt that stalking is a crime."

The British Crime Survey estimated that approximately 120,000 incidents of stalking occur each year. Between 2009 and 2010, however, just 53,000 crimes of stalking or harassment were recorded by the police: 2% of which received a custodial sentence, and a further 10% of which were given a fine or a probation order.

The reforms are thought to be similar to those introduced in Scotland in December 2010. Since the introduction of the stalking law in Scotland there have been over four hundred400 prosecutions compared with an average of seven per year under existing breach of the peace legislation for each of the previous 10 years.