DUBLIN, Jan 3 (Reuters) - Growth in Irish manufacturing activity eased further in December from record highs reached earlier in 2021, a survey showed on Monday, at the end of the third-strongest quarter on records going back more than 20 years. The AIB IHS Markit manufacturing Purchasing Managers" Index (PMI) fell to 58.3 in December from 59.9 in November, having hit a record 64.1 in May, the survey showed. Readings above 50 indicate overall rises in activity. From October to December, the PMI registered 60.1, down from 62.1 in the third quarter and 62.9 in the second but higher than in any previous quarter since the survey began. Cost pressures remained intense with raw materials, fuel, energy and transport charges cited as driving inflation. While the input prices subindex eased to a three-month low, it was still higher than at any period prior to October"s peak. Manufacturers continued to pass higher costs on to customers, with output prices increasing at the third-fastest rate since the data series began in 2002. "Manufacturing production is still expanding at a rapid pace, with new orders recording another marked rise, though growth in export orders remains muted," AIB chief economist Oliver Mangan said. "Employment in the sector continued to grow at a solid pace. Meanwhile, manufacturers were very positive on the 12-month outlook for production, with sentiment hitting its best level since July."