UPDATE 1-Brexit deal made harder by May comments - EU official

British Prime Minister Theresa May's speech to the UK parliament on Monday has shown that reaching a deal on the country's exit from the European Union will be even harder than expected, a senior EU official said on Tuesday.

May urged the EU not to allow a stand-off over a 'backstop' for Ireland to derail Brexit talks, saying she believed a deal was still achievable.

Her speech and subsequent answers to lawmakers' questions are not helping the process, the official said.

"They demonstrate that finding an agreement will be even more difficult than one could have expected," the official said.

A summit of EU leaders this week will decide if there is enough progress for another summit on Brexit in November, the official said.

The 27 countries remaining in the bloc after Britain's exit at the end of March 2019 insist that the economic part of May's plans for future relations with the EU will not work, the official said.