Turkish officials said a labor shortage is apparently forcing Bulgaria to slow the flight of ethnic Turks across the border. “About 4,000 of our kinsmen are still arriving each day, but newcomers say there has been a slowdown in giving new passports,” Gov. Unal Erkan of Turkey’s Edirne province said. Other officials said they had reports that Bulgaria recently stopped issuing new passports until Sept. 1 and is keeping back young men for military service. About 100,000 ethnic Turks have fled across the border in recent months, and Bulgaria received 300,000 applications in 15 days last month by those seeking to avoid forced assimilation by Bulgaria.