ST PETERSBURG, Russia (Reuters) - The Greek government hopes Monday's last-ditch summit of euro zone leaders to resolve the standoff between Athens and its creditors can help produce a result, an official said on Thursday. "We hope that Monday's summit is productive," said the official, who was travelling with Prime Minister Alexis Tsipras on a visit to St Petersburg. He gave no other details. (Reporting by Renee Maltezou)