Britain's interior minister Priti Patel suggested in an interview published on Saturday that a European court's intervention to stop a deportation flight to Rwanda was politically motivated.

"You've got to look at the motivation," she told the Daily Telegraph, after the European Court of Human Rights (ECHR) stepped in on Tuesday, just as the flight was due to leave for Kigali.

"How and why did they make that decision? Was it politically motivated? I'm of the view that it is, absolutely.

"The opaque way this court has operated is absolutely scandalous. That needs to be questioned."

Patel said the government had not been told the identity of the ECHR judges and had not received the full ruling of the order not to remove the migrants until a review of the policy was complete.

"They've not used this ruling previously, which does make you question the motivation and the lack of transparency," she added.

The UK government, which promised to tighten borders after Brexit, is under pressure to deal with record numbers of migrants crossing the Channel in small boats from northern France.

More than 11,000 people have been intercepted and brought ashore so far this year -- almost double the number at the same time 12 months ago.

But a controversial deal signed with Rwanda to send some asylum seekers on a one-way ticket for resettlement in the east African country has caused outrage.

Some 130 asylum seekers were originally scheduled to be on Tuesday's flight but the numbers were whittled down to zero after a series of legal challenges on human rights grounds.

The government in London is considering rewriting the UK Human Rights Act, which is based on the European Convention of Human Rights, to make it easier for it to deport migrants.

Prime minister Boris Johnson has criticised lawyers for taking on asylum cases and Patel's claim of a political dimension to the EHCR decision fits into to a government narrative about threats to UK sovereignty by European bodies.

But the rights court is not part of the European Union, which the UK left in January last year, and London helped to set up the tribunal and draft the convention.

Patel said the government would not be deterred, and her Home Office department has embarked on a 12-month pilot project to electronically tag some migrants.

It said the scheme "will test whether electronic monitoring is an effective means by which to improve and maintain regular contact with asylum claimants who arrive in the UK via unnecessary and dangerous routes and more effectively progress their claims toward conclusion".