-Turkish tensions have risen over USA military support for Kurdish YPG fighters in Syria, considered by Ankara to be an extension of the banned PKK, which has waged an insurgency for three decades in southeast Turkey.
The dispute blew up last week when Turkey arrested a Turkish employee of the American consulate on suspicion of links to the group blamed for last year's failed coup.
Erdogan arrived in Belgrade on October 10 on a two-day visit that analysts say is a bid to increase Ankara's clout in the Balkans.
Sandzak, where many people consider Bosnia or Turkey - rather than Serbia - as their motherland, has remained peaceful but tense over the years.
Turkish President Recep Tayyip Erdogan received a rousing welcome on Wednesday as he visited a predominantly Muslim region in southwestern Serbia.
Turkey is calling for a normalization of relations with the United States following rising diplomatic tensions between the North Atlantic Treaty Organisation allies.
Turkish officials had expressed hope of a new page in Ankara-Washington relations under President Donald Trump after repeated bickering in the last months of Barack Obama's term.
"In order to minimise the number of visitors to our diplomatic and consular missions in the USA while this assessment proceeds, effective immediately we have suspended all visa services regarding the United States citizens at our diplomatic and consular missions", it added. Bass is at the end of his posting and is due to leave Turkey at the weekend.
"Today, taking into account the latest developments, we chose to bring our turnover to a level of 10 billion dollars as soon as possible", he said.