Children being cared for by relatives other than their parents is most common in the north-east of England, while grandparents feature in the majority of such arrangements across the country, according to new statistics.

The total number of children in so-called kinship care across England and Wales was estimated to be around 141,000 at the time of the census in 2021, the Office for National Statistics (ONS) said.

But the organisation cautioned that this was only a “rough estimate” and said its analysis, published on Tuesday, is based on kinship care in households of five people or fewer – which totalled around 121,000 children.

Kinship care is defined as when a child – someone aged 17 or under – lives full-time or most of the time with a relative or close family friend, usually because their parents are not able to care for them, the ONS said.

The statistics body said while there appeared to have been a decrease in the number of children living in kinship care, from 145,000 children in 2011, estimates cannot be directly compared because the quality of household relationship data improved in Census 2021.

Charities in the sector have said they believe there is more likely to have been an increase and “reflecting rising levels of child poverty and other factors which influence child welfare intervention”, with one organisation criticising the “current disparity” in data collection as “unacceptable”.

The latest findings suggested that the north-east of England has the highest proportion of kinship care households (2.3%), while the south-east and east of England had the lowest proportions (both 1.2%).

More than half of children living in kinship care live with at least one grandparent (59.2% or 72,000), the ONS said.

Steve Smallwood, from the ONS, said it is “striking how important grandparents are in providing care”, adding that this explains why many such households are characterised by people living there who are less likely to be employed and who are in poorer health.

The figures come as Tesco became one of the first UK retailers to give kinship carers the same support as adoptive parents.

The supermarket giant said the kinship leave is intended to help such carers stay in the workforce, while managing their extra responsibilities.

Under the new arrangements, staff who have a Special Guardianship Order to care for relatives’ children will get 26 weeks’ leave on full pay, Tesco said.

The ONS statistics showed that, in England, the top three local authorities with the highest proportions of kinship care households were Hartlepool, Middlesbrough, Redcar and Cleveland – all in the North-East.

In Wales, the top three local authorities were Merthyr Tydfil, Blaenau Gwent and Caerphilly.

The statistics also showed that just over one quarter (25.9%) of children in kinship care live with two potential carers who are grandparents, followed by one potential carer who is an “other relative” (24.5%), and one potential carer who is a grandparent (20.2%).

Some 11.9% of children living in kinship care are disabled – higher than the 6.6% of children who are disabled and living with at least on parent.

One quarter (25.3%) of kinship care households contain one or more people whose long-term physical or mental health condition or illness limits them a lot, compared with 10.0% of parental households, the ONS said.

Kinship, a charity supporting such families, said while the latest data is useful it “isn’t enough to give us the accurate and robust understanding of kinship families” needed to inform policy.

The charity there is an “unacceptable” disparity in data collection for this group and said their own figures will combine the latest census data as well as other sources including local authorities and the Department for Education.

The charity said: “The invisibility of kinship families allows children and their carers to remain invisible to policymakers – this must end if we are serious about truly transforming support for kinship families of all types throughout England and Wales.”

The Government has pledged to publish a national kinship care strategy by the end of 2023.

Cathy Ashley, chief executive of Family Rights Group, said kinship carers often face barriers to support and many have to give up work to take on caring responsibilities, “driving them into poverty” while the children may not always get the professional support they need to deal with their tragedy or trauma.

She said: “Kinship carers are doing right by the children, now it’s time for Government to do right by kinship care by raising its ambitions in the upcoming kinship care strategy.”

Kinship, which has campaigned for paid kinship care leave on a par with adoption leave, welcomed Tesco’s new policy, and urged other retailers to “follow their lead”.