Three of the world’s rarest birds have been trapped at a secret bird sanctuary by legal procedures for three years despite efforts by Brazil to get them back.

There are 246 Lear’s macaws left in the wild and environmentalists are anxious to have the three returned to their jungle homeland for a breeding programme. They have been held in a Yorkshire aviary since they were seized by Customs in 1998 after having been smuggled into England.

Boris Johnson, the Tory MP for Henley, is to raise the case in Parliament and Celso Amarim, the new Brazilian Ambassador is expected to take it up with British officials when he arrives this month.

The blue and yellow birds are found wild exclusively in the Bahia region of Brazil where they nest in sandstone cliffs and eat fruit from licuri palm trees. The Brazilians want to breed from them to lessen the threat of extinction.

A spokeswoman at the Brazilian Embassy in London said yesterday that there had been several exchanges of letters with the British Government. "We have even sent an official note to the Foreign Office raising our concerns," she said. "We think it is taking an extraordinary long time. People in Brazil are getting impatient."

Mr. Johnson said " I hope that people will back me in a campaign to free the Brazilian Three. I do not believe the British taxpayer will indefinitely pay for the incarceration of these beautiful creatures, especially when we are not even able to see these gorgeously plumed birds."

He will raise the matter this week with Lord Goldsmith, the Attorney General and Paul Boateng, the Treasury Minister responsible for Customs and Excise, to demand " speedy repatriation of the birds"

A Customs spokesman said that the Government wished to return the birds, but did not yet have legal ownership of them. He said that Customs had to apply in the Crown Court for anything it seized. "This can be a protracted procedure, but we hope it will be resolved. It has been held up by other legal complications."

The birds were smuggled into Britain from Eastern Europe by Henry Sissen, a bird breeder from Northallerton, North Yorkshire. They were seized from his farm in May 1998 and in April last year he was sentenced to prison for 21/2 years, reduced on appeal to 18 months.

He has now been released and is appealing against an £ 150,000 confiscation order, deemed to be the profits from his illegal activity and seizure of the birds.

There is a breeding pair of eight or nine-year-olds and a female of about 11 or 12 years. On the black market they could fetch up to £ 80,000 and are being held in an aviary with alarms, closed- circuit television, movement sensors and security lights. The birds can live up to 50 years.

The head-keeper said, " The pair are very friendly together, but there have been no eggs." The birds are fed once a day on seeds, grains, walnuts, hazel-nuts and pine-nuts and are also treated to helpings of apple, pear, banana, pawpaw, seedless grapes, carrots and cabbage. The keeper said, "They are very, very loud screechers."