NEW YORK (CNN/Money) - Growth in the service sector showed an unexpected pick up in March, while expansion in manufacturing held steady, according to closely watched surveys of business executives.

Both surveys are conducted among purchasing managers by Institute of Supply Management. The services sector survey, originally scheduled to be released Tuesday morning, was mistakenly released Friday when the manufacturing survey was due.

The erroneous release caused confusion on Wall Street, with investors momentarily trading on the wrong set of numbers.

The services sector index came in at 63.1, up from 59.8 reading in February. Economists surveyed by Briefing.com had forecast a decrease to 59.0.

The manufacturing sector index came in at 55.2 in March, down slightly from 55.3 in February. But that topped economists' average forecasts of 54.9, according to Briefing.com.

Any reading above 50 indicates growth in the sector being measured.

The March survey marked the 22nd straight month of manufacturing growth, which made it the longest expansion of that sector since 1998.

CNN/Money erroneously reported both the manufacturing and the non-manufacturing index numbers earlier in the day Friday. We regret the error.