Japan's service-sector activity extended gains in August, a private sector survey showed on Wednesday, thanks to an uptick in overseas sales despite a darkening global outlook. The final au Jibun Bank Service purchasing managers' index (PMI) was unchanged at 53.7 last month, staying above the 50.0 line that separates expansion from contraction for a second consecutive month. While the headline figure was in line with July's reading, service companies' new business growth slowed from the previous month. But export sales rebounded from a contraction in July to the largest rise in three months, supporting overall service-sector business.