May has said she would start two years of talks on leaving the bloc by the end of March and on Tuesday she outlined her plans for the upcoming negotiations.
"I must be clear Britain wants to remain a good friend and neighbour to Europe," she said.
"Some voices are calling for a punitive deal, that punishes Britain and discourages other countries from taking the same path. That would be an act of calamitous self-harm for the countries of Europe and it would not be the act of a friend."
She said Britain would not accept such an approach but was sure a positive outcome could be reached.
"I am equally clear that no deal for Britain is better than a bad deal for Britain."
(Reporting by Paul Sandle; editing by Stephen Addison)
