The number of available jobs in the US grew in August, signaling an undercurrent of strength in the labor market at a time when its vitals are being carefully monitored by the Federal Reserve.

There were 8 million job openings in August, up from 7.7 million in July, the Bureau of Labor Statistics said Tuesday. It was the first increase in three months and was higher than the 7.7 million forecasters had expected, according to a survey of economists by Dow Jones Newswires and The Wall Street Journal.

The Labor Department reported Tuesday that employers posted 8 million vacancies in August, up from 7.7 million in July. Economists had expected openings to be virtually unchanged. Openings were up in construction and in state and local government.