Police forces across Britain and Ireland have commenced an unprecedented crackdown on human trafficking, aiming to reach out to women and children forced to work in the sex industry, and to prosecute gangs profiting from the illegal trade.

Jacqui Smith, the British Home Secretary, said that the crackdown would allow a clearer picture to be drawn of the extent of the "secret" crime.

The move will come as good news to campaigners who have urged the Government to commit more funding towards eradicating the form of modern-day slavery. Ms Smith said that the Government has invested "significant resources" into tackling the problem.

The new operation, codenamed Pentameter 2, will involve all 55 police forces in the UK and Ireland, and will be guided by the dedicated Human Trafficking Centre in Sheffield which was established last year.

In 2006 a similar operation, helped to free 84 women and teenage girls from illegal brothels and "massage parlours", and resulted in 232 arrest warrants being issued.

Gloucestershire Chief Constable Dr Tim Brain, speaking to the BBC, said the new initiative would aim to gather intelligence, enforce the law and rescue victims. He said, "A lot of it is intelligence gathering for now and for the future.

"So it's to improve our picture but equally at the same time to ensure that we go after these gang masters, the people who are exploiting the women, and bring them to justice."

He added: "It's a secret crime so nobody has a real idea of just how big it is, but the indications are that it is growing.

"It's a very profitable crime for the criminals who work these women. We expect it to grow unless we do something about it."

The Government pointed to new research suggesting that up to 4,000 women in the country were working in areas of sexual exploitation. However, the home secretary also said that there is no evidence it is an escalating problem.

Ms Smith said that research indicated women and children were being trafficked from in and outside Europe, and even within the UK itself. She said: "Two hundred years after we banned the trade in slavery in Parliament in the UK, it's shocking that this is still going on."

The public have been urged to play a part too, by reporting any suspicious behaviour to the police, and a new telephone line will be set up to offer advice to immigration staff and social workers to help identify trafficked victims.

The crackdown comes one week after CHASTE (Churches Alert to Sex Trafficking across Europe) announced it will tour the UK in November with the message that love is not for sale.

CHASTE Chief Executive Dr Carrie Pemberton said of the tour: "The same goal, making money out of the suffering of others, was behind the transatlantic slave trade two hundred years ago. Now we have a movement arising in both Parliament, the academy, the police, the churches and the faith communities which is saying 'enough is truly enough'."