NEW YORK (Reuters) - December’s gain in U.S. private payrolls reported by ADP Employer Services was the “most robust number” on record, with data going back to 2000, Macroeconomic Advisers LLC Chairman Joel Prakken said on Wednesday.

Prakken was speaking after the ADP report, jointly developed with Macroeconomic Advisers, showed private employers added 297,000 jobs in December, about three times as much as forecast by economists surveyed by Reuters.

He noted seasonal factors may have boosted the December numbers but said: “It looks to me growth in employment has moved ... comfortably into positive territory and seems to be accelerating.”

Prakken said he’s confident Friday’s U.S. Labor Department nonfarm payrolls report will show a “healthy number.”

Friday’s report is forecast to show nonfarm payrolls rose 140,000 in December, with a gain in private payrolls of 145,000, according to a Reuters poll.

Also. Prakken said, “Gains we reported were widespread ... and for the first time in years there was no decline in construction employment.”