ANKARA - Iranian Foreign Minister Mohammad Javad Zarif is to visit Turkey on Wednesday at his own request, Turkish foreign ministry sources said, as a dispute between Gulf powers and Qatar escalates.The sources said Zarif would discuss bilateral and regional matters. Efforts to defuse the Qatar crisis -- prompted on Monday when the UAE, Saudi Arabia, Egypt and others severed diplomatic ties with it over alleged support for Islamist groups and Iran -- have showed no immediate signs of success.Turkish President Tayyip Erdogan, who has been on a push to resolve the crisis, has said that isolating Qatar, including by the use of sanctions, would not resolve the rift."It will not contribute to solving any problem to try and isolate in this way Qatar, which we know for sure has fought very effectively against terrorist groups," he said following a fast-breaking dinner for the Muslim holy month of Ramadan on Tuesday.Erdogan has been in talks with the leaders of Qatar, Russia, Kuwait, Saudi Arabia and others on lowering the tension."We appreciate the cool-headed and constructive attitude which Qatar has shown," he said. "We as Turkey will continue to develop our relations with Qatar as with all our friends."Turkey has good relations with Qatar as well as several of its Gulf Arab neighbors.Qatar has for years parlayed its enormous gas wealth and media strength into broad influence in the region. But Gulf Arab neighbors and Egypt have long been irked by its support for the Islamist Muslim Brotherhood, which they regard as a political enemy.