European citizens should not go into a "bureaucratic nightmare" after Brexit, a top MP, to stay in the UK.
Guy Verhofstadt told the European Parliament that the three million EU citizens in the UK would need to be able to secure their future rights easily.
"After the Windrush scandal, we want to be sure our Europeans are not going to," he said.
Ministers say that people have limited information to provide
The United Kingdom and the EU have reached an agreement on the rights of residents after the UK's exit from the EU, although only so then, when an overall withdrawal is agreed
All EU citizens entering before the Brexit day in March 201
However, you must apply for a fixed status or a temporary residence permit.
The ministers have stated that there will be a presumption that this will be granted in almost all cases, and unlike the previous process of applying for permanent residence, where an 85-page document was completed, it will only little paperwork involved.  But questions have already been asked about the Ministry of the Interior's ability to handle so many requests in a relatively short time.
And during a debate in Strasbourg, MEPs pointed to the ongoing Windrush deportation series in the UK – where the children of Caribbean migrants who settled in the UK from the late 1940s to the 1970s, but no formal documents have faced uncertainty about their future due to recent changes in immigration legislation.
Guy Verhofstadt, leader of the Liberals The ALDE Group and Parliament's Chief Speaker, Brexit, have already expressed their concern that EU citizens may be "exposed to similar treatment".
He and other MEPs will meet with Ministry of Interior representatives next week to discuss the details of the registration system proposed by the UK.
"Things are not over yet," he said Wednesday.
"We Need to If changes are needed, we will tell negotiators what changes are needed to avoid real problems for our EU citizens."
- Katya Adler: Why Brussels relaxes over the Brexit final  The BBC's European reporter, Adam Fleming, said he understood the windrush situation during a meeting of the European Parliament's Brexit Steering Group led by negotiator Michael Barnier.
Ministers say the registration system for EU citizens will operate in the EU in the second half of the year and will remain open until 30 June 2021.
Applicants will need a "ID card" and a recent photo and, to minimize the need for supporting evidence, the Home Off ice says it will use government data, such as the employment records of the UK tax authority.
Officials have said that applicants do not have to report every trip they have made from the UK and that the forms are not denied "simple mistakes or omissions".
Unlike other applicants, existing permanent residents do not have to pay a fee to re-apply, nor do they need to provide additional evidence that they still live in the UK.
The ministers have insisted that applicants only for safety or if they have serious criminal convictions.