By Francois Murphy

VIENNA, June 17 (Reuters) - The most important issue in imminent nuclear talks between Iran and the United States is how Iran's nuclear programme will be policed, Saudi Arabia's Foreign Minister Prince Faisal bin Farhan said on Wednesday.

Washington and Tehran say they have reached an agreement to end their war and open wider talks on issues including Iran's nuclear programme. A senior U.S. official read out the text of a memorandum of understanding with Tehran but said the parties could still walk away until a binding deal is reached.