Nearly 15,000 days were lost to industrial disputes last year, according to new figures published by the Central Statistics Office (CSO).

This marks a sharp increase on the 8,486 days lost to disputes in 2012.

There were twelve industrial disputes reported in total in 2013, up from just five in the year before. The twelve disputes involved 11,924 employees at 12 firms.

More than 65 per cent of the days lost last year were due to two disputes in the transportation and storage sector, where workers from Bus Éireann and Dublin Bus held strikes.

The two disputes accounted for 9,815 of the total days lost last year.

In the fourth quarter of 2013, a total of five disputes were in progress, involving 6,394 workers and five firms. Of these, four of the disputes began in the final three months of the year, with one other dispute having carried over from the previous quarter.