British citizens with foreign-born partners are to be given the choice of indefinite "exile" in countries including Yemen and Syria or face the breakup of their families if they want to remain in the UK, under radical immigration changes to be announced next week, MPs have been told.

The home secretary, Theresa May, is expected to confirm that she will introduce a new minimum income requirement for a British "sponsor" without children of up to £25,700 a year, and a stringent English speaking test for foreign-born husbands, wives or partners of UK citizens applying to come to live in Britain on a family visa.

Immigration welfare campaigners say that the move will exclude two-thirds of British people – those who have a minimum gross income of under £25,700 a year – from living in the UK as a couple if they marry a non-EU national. They estimate that between 45% and 60% of the 53,000 family visas currently issued each year could fall foul of the new rules.

Ministers have also been considering extending the probationary period for overseas spouses and partners of British citizens from two to five years and introducing an "attachment test" to show that the "combined attachment" of the couple is greater to Britain than any other country.

The changes are to be introduced alongside new immigration rules, making clear that an illegal migrant or a convicted foreign national facing deportation who has established a family life in Britain will only be blocked by the courts from being removed, under article 8 of the European convention on human rights, in rare and exceptional cases. Instead they, too, will face a choice between separating from their British-based spouse or partner or going to live with their partner as a family overseas.

The moves to restrict the family route for migrants coming to Britain form part of the home secretary's drive to reduce net migration from 250,000 to "tens of thousands" by the next general election.

The Joint Council for the Welfare of Immigrants (JCWI) has sent MPs a dossier of 13 detailed cases of families who would face serious consequences under the proposals, "to provide a snapshot of the reality of the lives of ordinary British citizens and settled people who want their husbands, wives, civil partners and in some cases children to join them in the UK".

It includes the case of Anna, a British woman who is pregnant with twins, earning £31,000 a year, who may have to give up her home, job, flat and friends in the UK and move to Yemen to live with her husband, Ahmed, at a time when the Foreign Office has advised British nationals not to travel there. The fact that Anna is expecting twins means the minimum income maintenance requirement in her case will be set in a range from £24,800-£46,260, rather than at the childless couple rate of £25,700.

It also highlights the case of Emma , a British graduate who works, and is due to complete a journalism course this year, who may also have to give up her flat, family and friends in Britain, and travel to Syria where her Palestinian husband was born.

The JCWI says that the dossier shows how the ordinary circumstances of life, such as pregnancy, accidents at work, disability, low pay, poor currency exchange rates and nationality laws in foreign countries could penalise people if the proposals make it into Britain's immigration rules.

The dossier also highlights how an extension of the probationary period for those granted family visas could trap more women in violent marriages and suffering domestic abuse in silence because of the fear of being deported if they complain.

"When, if ever, is it acceptable for British citizens to be placed in a position where they are effectively indefinitely exiled from their own country on account of choosing to have a relationship with a non-European Economic Area national?" asks the JCWI pamphlet, United by Love/Divided by Law?

When the home secretary published her proposals in May she said that it was obvious that British citizens and those settled here should be able to marry or enter into a civil partnership with whomever they choose: "But if they want to establish their family life in the UK, rather than overseas, then their spouse or partner must have a genuine attachment to the UK, be able to speak English, and integrate into our society, and they must not be a burden on the taxpayer. Families should be able to manage their own lives. If a British citizen or a person settled here cannot support their foreign spouse or partner they cannot expect the taxpayer to do it for them."