Manufacturing slowed in May as the sector lost momentum, held back by sharp slowdowns in the growth of output and new orders, new data showed.

The NCB Manufacturing PMI, which provides a measure of the health of the manufacturing industry, fell to 51.8 from 56 in April, while output index fell to 52.6 from 58.7, the weakest rise in six months.

"The reading indicated that while operating conditions in the sector strengthened again over the month, the improvement was the weakest since November 2010," NCB said.

Chief economist at NCB Brian Devine said it was "worrying" that the index was falling towards 50 once more, suggesting that the pace of activity in the manufacturing sector generally is slowing.

The expansion in new orders was also at a six-month low, falling to 52.9 from 57.3 a month earlier and 57.9 in March.

In response to lower growth, firms cut employment and purchasing activity, leading to a slight drop in employment during May, the first fall in five months. Higher prices for oil and steel drove average input prices sharply higher, while output prices also climbed in response.

However, new export orders continued to expand strongly, with the index at 58.7, slightly lower than April's reading of 59. NCB said respondents to the survey had reported strong overseas demand, particularly from the UK.