The government has suffered a narrow defeat in the House of Lords over its Modern Slavery Bill.

Peers voted in favour of an amendment designed to give greater protection to overseas domestic workers.

The new clause - adopted by 183 votes to 176 - would allow domestic workers brought into the country by a foreign family to change employer.

The BBC's Sean Curran said the move by peers was a challenge to the UK system of "tied visas".

The Modern Slavery Bill has already cleared the House of Commons. When it returns to the House, MPs would have to agree to the new amendment for it to become law.

Rule changes

The amendment - which attracted cross-party support - was put forward by independent crossbench peer Lord Hylton, and backed by the Bishop of Carlisle.

It would give all overseas domestic workers, including people working for foreign diplomats, the right to change their employer while in the United Kingdom, ending the current system of tied visas.

The proposal would also give the workers the right to a three-month temporary visa to live in the UK where there was evidence that the person had been a victim of modern slavery.

Under previous rules overseas domestic workers were at first given temporary permission to stay and could eventually settle permanently.

But changes introduced by the government in 2012 meant that workers could not change jobs or renew their visas if they left their employer.

Image caption Domestic workers protested against immigration rules in London last year

The government said at the time that the arrangements should be brought into line with an immigration policy focused on only accepting highly skilled workers to the UK.

But charities say the rules must be reversed as they allow abusive employers to demand extremely long hours, and withhold pay and food.

The amendment approved by the House of Lords on Monday evening partially overturns the 2012 change.

Rebel peers

Lord Hylton argued that the current rules contained "a loophole for abuse". Explaining the purpose of his amendment, he told peers: "It will assist all private and diplomatic domestic workers by providing a measure of protection and flexibility that is otherwise lacking in the bill."

It attracted the support of Labour, with shadow Lords leader Baroness Royal of Blaisdon saying the government's promise of a review on the issue to report by July was unnecessary as the problem was already well documented.

"These workers need a change in the law and we have an opportunity today to make that a reality," she said.

Image caption Lord Hylton has been a long-time campaigner for protection of domestic workers

Home Office Minister Lord Bates said the last Labour government introduced the overseas domestic worker visa to facilitate people coming to the UK for short visits to bring their own household staff, and that the average length of such visits was still only 15 days.

He warned that the change being proposed would open up the opportunity for the visa to be "potentially used as another way in which labour can enter the UK".

He insisted there were a range of measures, some introduced by the bill, to help enslaved domestic workers. But he said a review was needed to examine the operation of the visa, after which the rules on it could be changed without the need for primary legislation.

However, despite his assurances, peers voted for the amendment, defeating the government by a majority of seven.

Later analysis of the division showed there was one Conservative rebel - Baroness Hanham - and one Lib Dem rebel - Baroness Hanwee. It was also backed by 135 Labour peers, 35 crossbenchers, four bishops and seven others.