Martin Schulz, president of the European Parliament | EPA/Patrick Seeger Schulz: Many MEPs say ‘let Britain leave’ European Parliament president says UK is testing EU’s patience.

Discrimination against EU migrants in the U.K. remains unacceptable for the European Parliament while many in the assembly now think "if the Brits want to leave, let them leave," its president warned Friday.

"Proposals which cater to narrow self-interests risk undermining the common good," Martin Schulz said at the London School of Economics, adding this would set a dangerous precedent for a "Europe à la carte."

Giving his assessment of the draft deal released by European Council President Donald Tusk on Tuesday, Schulz said: “Parliament needs to see its concerns addressed early,” to avoid it becoming a roadblock later in the legislative process. The Parliament has had a minor role in U.K. Prime Minister David Cameron's negotiations until now, though it must vote to approve some elements, including the controversial 'emergency brake' to limit EU migrants' in-work benefits during their first four years in the U.K..

Schulz imagined a scenario where a German working in London in 2017 received less benefits than her British colleague, while that colleague's son in Berlin enjoyed the same welfare arrangement as Germans.

“Is this the EU we want to live in?” Schulz asked.

Some limits on free movement were acceptable, he said, should this be shown to be contributing to problems such as overcrowded schools and stretched hospitals. But he said the European Parliament would not support solutions that "cause discrimination" and "undermine EU values."

Schulz said "the British often test our patience and good will with their continuous demands."

"They are demanding. They push hard. They insist. They just don't let go. Many of my colleagues say behind closed doors: 'Don't stop a rolling stone. If the Brits want to leave, let them leave.'"

But the German Socialist maintained he was a keen supporter of Britain remaining in the EU.

"I do not support this line that just because the U.K. can be frustrating it would be in our interest to let it go. I believe we need the U.K. to make the EU stronger and better."