WASHINGTON (AFP) - The US private sector hiring accelerated in June, payroll firm ADP said on Wednesday in a positive sign for the official jobs report this week.

Businesses added 237,000 positions last month, up from 203,000 in May and the best level since December.

Over half of the hiring came from small businesses, those with less than 50 employees.

There was strength in construction, adding 19,000 jobs; professional and business employment, 61,000 positions; and trade, transportation and utilities, 50,0000 positions, ADP said.

"The US job machine remains in high gear," said Mark Zandi of Moody's Analytics, which helps compile the data.

"The current robust pace of job growth is double that needed to absorb the growth in the working age population. The only blemish in the job market is the loss of jobs in the energy sector," he said.

"Most encouraging is the healthy rate of job growth among the nation's smallest companies." The ADP report was a good sign for the Labor Department's June jobs market report to be released on Thursday.

Analysts expect the official assessment of both public and private sector hiring will show 230,000 net new jobs created, with the unemployment rate falling a tick to 5.4 per cent.