Private sector in the U.S. added 237,000 jobs in June, according the ADP report on Wednesday. It was the biggest increase since December 2014.

May's figure was revised up to 203,000 jobs from a previous reading of 201,000 jobs.

Analysts expected the private sector to add 217,000 jobs.

The increase was driven by a job creation in the professional and business service.

"The U.S. job machine remains in high gear," the Chief Economist of Moody's Analytics Mark Zandi said.

Official labour market data will be released on Thursday. Analysts expect that U.S. unemployment rate is expected to decline to 5.4% in June from 5.5% in May. The U.S. economy is expected to add 232,000 jobs in June, after adding 280,000 jobs in May.