"President Juncker followed prime minister May's announcements this morning without personal joy. The president very much liked and appreciated working with prime minister May, and as he has said before, Theresa May is a woman of courage for whom he has great respect," the spokeswoman said.

She added that Juncker would "equally respect and establish working relations with any new prime minister whomever they may be."

May's announcement came shortly after she presented a new Brexit plan that was met with criticism in her own party.

The European Commission reiterated Thursday it would not renegotiate the withdrawal deal, but could review the political declaration on future ties.

"Our position on the withdrawal agreement and anything else has been set out ... yesterday ... There is no change to that," Andreeva said.