Labour Shadow Chancellor John McDonnell described the talks as "positive" and "constructive" but refused to reveal whether the Government had moved on any of its red lines.
May and Corbyn will continue talks this week after the prime minister secured an extension to the Article 50 deadline on Wednesday.
David Lidington, who is leading the talks with Labour on subjects such as environmental standards, workers rights and the security relationship with the European Union, said the discussions were going to continue next week but that they wouldn't last months.
He also noted that the party "should never have allowed legitimate criticism - that I share - of the current Israeli government to act as a cover for the demonization of the entire Jewish people".
British Prime Minister Theresa May leaves the Elysée Presidential Palace after a meeting with French President in Paris, France, 09-04-2019.
The Democratic Unionists are supposed to support the government in key parliamentary votes to give it a majority in the House of Commons.
Despite the best efforts by Remainers to use European Parliament elections to their advantage, think tank Open Europe said last week that the polls are likely to result in a "protest" vote, where Britons will "send a message" to the establishment, punishing them for failing to deliver Brexit.
"I don't want to compromise what is at the moment a space where we are testing with the opposition, and they are testing with us, particular ways in which we could move forward".
"If, on the other hand, we do offer clarity and a confirmatory ballot, we could do very well".
"Pro-Remain parties the Greens, Liberal Democrats, and the newly-formed Change UK (CUK), previously known as The Independent Group (TIG), and other breakaway Europhile groups hope to use the European Parliament elections as a "soft referendum" to show support for remaining in the EU". But with Parliament still deadlocked on whether to accept that the government's divorce handle the bloc, European Union leaders have stalled Brexit until October 31.