BELFAST (Reuters) - The head of the Northern Irish party which props up the British government spoke to Prime Minister Theresa May on Monday shortly after telling supporters she would not allow a Brexit deal that creates  regulatory divergence  between the region and Britain. Democratic Unionist Party leader Arlene Foster spoke to May by phone shortly after her statement in Belfast, a party source told Reuters. The source declined to reveal the content of the call, but said the DUP was in continuing contact with May.  May agreed on Monday to keep Northern Ireland in  regulatory alignment  with the European Union after Brexit, Irish government sources said, creating the possibility of divergence between regulations in Northern Ireland and the rest of the United Kingdom. 