Thousands of British families will be kept apart following a court decision which ruled it was legal to put an income requirement on people bringing foreign spouses to live with them in the UK.

Under rules introduced by Theresa May, Brits are required to earn at least £18,600 before they can bring their foreign spouse to the UK, although the benchmark rises to £22,400 for couples with children.

The rule was branded "disproportionate and unjustified" in the high court, but today's appeal ruling puts campaigners back at step one and spells despair for many families who have been separated for months as they awaited the outcome.

The three judges ruled "all immigration law is inherently discriminatory" but in this case found the income benchmark to be "justified".

"This judgement will be devastating for the families who continue to be needlessly separated across borders," Ruth Grove-White, policy director at the Migrants Rights Network, said.

"Many UK residents and British citizens have had their lives put on hold for over a year, often with no chance of seeing their loved husbands, wives or children during that time.

"These rules are a shocking infringement of the right to family life, as almost half of the UK working population earns below the required amount. Being able to start a family in your own country should not be subject to the amount of money you make.

"Today's judgement is not the end of the story. We will keep campaigning for rules that respect the right of UK residents to live with their family, and hope that government will see sense and make the changes that are needed to protect these rights."

Paul Blomfield, chair of the all-party parliamentary group on migration, said: "Today's court of appeal judgement will come as a disappointment for the thousands of families across the UK who remain apart as a result of these rules.

"A year ago, a cross-party group of MPs recognised the anguish they have caused and urged the government to review the family migration rules. That concern was highlighted again this week in a packed meeting in the House of Commons.

"On behalf of our constituents, we will continue to press the government to think again."

Devastating news on the #MMCase judgement. But we must still keep up the fight. People have a right to be with their loved ones. — John Stuart Adams (@johnstuadams) July 11, 2014

Campaigners say the rules mean only the well-off are allowed to live with a foreign wife or husband in their own country.

Someone working full time on minimum wage would be almost £5,000 short of the benchmark. Under the system, 40% of the British working population are prevented from bringing a foreign spouse to live with them.

Spouses coming to Britain who command high salaries cannot have their current or expected salary used to satisfy the requirement.

Disappointingly, this governments anti-family immigration policy upheld, shameful that Tories ever dare speak about family values - #MMcase — Dan Bunting (@danbunting) July 11, 2014

Friends and family are not allowed to state that they are prepared to support the couple, as is possible in other visa categories.

Freelancers, who can earn considerable sums one month and very little the next, are also badly affected, because they have to show six months of income statements above the threshold.

#MMcase What Hope Is they if the judiciary Can not denote injustice ...Price tag on Love. Love Is for the rich — Tapiwa (@TJTLaw) July 11, 2014

Only people with £62,500 savings for six months are exempt from the rule.

The appeal was a far cry from that of Mr Justice Blake, who previously branded the rule "disproportionate and unjustified" in the high court.

While he did not find that the rules were discriminatory or generally unlawful, he objected to the way the Home Office had ignored the benchmark suggested by the Migration Advisory Committee of £13,400 – a wage closer to the earnings of someone working 40 hours a week on minimum wage.

Disappointing decision in #MMcase but this is not end of the story. Fight goes on and we won't stop until we get rules protecting families! — Migrants Rights Net (@migrants_rights) July 11, 2014

Campaigners will now have to consider whether to try and take the case to the supreme court.

Labour pledged this week to review the rules if the party comes into power in 2015.