Europe's human rights watchdog has accused Britain of undermining the rights of gypsies and travellers to adequate housing.
Thomas Hammarberg, Commissioner for Human Rights at the Council of Europe, said the UK authorities had to provide such housing because it was "a pre-condition for the enjoyment of other human rights, including the rights to education and health".
A fortnight ago Mr Hammarberg wrote to secretary of state for communities and local government Eric Pickles, warning: "The continuing shortage of adequate permanent and transit sites for Gypsies and Travellers living in caravans is a priority area to address.
"By and large, local authorities have failed to provide new sites or refurbish existing sites in accordance with identified needs."
Referring to last October's evictions of travellers from the Dale Farm site in Basildon, Essex, Mr Hammarberg warned: "The rights to adequate housing of Travellers in Basildon have already been violated once. The authorities should ensure that no further violations take place, and should work responsibly towards a solution that is acceptable for all."
Replying this week Mr Pickles wrote that Britain has a strong and effective legal framework "which protects everyone, including gypsies and travellers, from discrimination".
But he acknowledged that "a shortfall of appropriate sites continues to be a problem in many areas", pointing out that between 2000-2010, the number of caravans on "unauthorised developments" grew from 728 to 2395.
Local authorities were best placed to assess the needs of their communities, wrote Mr Pickles, "so we are placing responsibility for site provision back with them".
He told Mr Hammarberg that the unauthorised traveller site at Dale Farm had been subject to an "exhaustive" legal process. The "clearance process" was a matter for Basildon District and had been "very much a last step in seeking to regularise the development of the site".
The letter insisted that throughout the process the lawfulness of the process had been tested and the unacceptability of the development confirmed: "We understand the local authority urged any occupant who did not have alternative accommodation to make a homelessness application."
Mr Hammarberg, publishing both letters today, said: "The rights of gypsies and travellers to adequate housing are undermined throughout the United Kingdom. The authorities must uphold this right."
His letter said last October's eviction of more than 80 traveller families from Dale Farm illustrated his concerns.
"It is highly regrettable that it was not possible for the relevant local authority to find an acceptable solution, respectful of the rights of all parties involved."
Many of the 400 or so travellers evicted had returned to the area, either to the authorised part of the site, or parking their trailers and caravans along the roads leading to Dale Farm.
"As a result, they are currently exposed to health and safety hazards. Basildon Council has indicated that there is a possibility of further action to remove these persons from the area, without offering culturally acceptable housing alternatives.
"The commissioner calls on the Secretary of State to ensure that local authorities are made aware of the United Kingdom's obligation to respect the right to adequate housing for all, including gypsies and travellers, and to deploy all efforts to identify sustainable solutions, respectful of cultural diversity."