The number of people signing on the Live Register rose by 13,500 to more than 400,000 last month, accoring to new figures from the Central Statistics Office (CSO).
The standardised unemployment rate in May was 11.8 per cent compared 11.4 per cent in April and 7.7 per cent at the end of December 2008.
At the end of May there were 402,100 people on the register, compared to 388,600 in April. During the month 8,800 men and 4,700 women joined the register.
In the year to May, there was a 96.7 per cent rise in the number of people on the register as 195,115 more people signed on. This compares with an unadjusted increase of 188,850 or 96.6 per cent a year earlier.
The estimated number of casual and part-time workers on the Live Register in May was 35,588 males and 30,590 females.
Fine Gael said that the figures contradicts reports that the economy is heading towards recovering.
“Ireland has the second highest unemployment rate in the euro zone. Every week in May, some 3,375 people lost their job. This puts paid to Brian Cowen’s spurious claim that the economy is showing green shoots of recovery," said Fine Gael Enterprise, Trade and Employment spokesman Leo Varadkar
The Labour Party described the latest figures as "truly shocking."
"This is the 19th successive month in which the numbers on the Live Register have increased. There are now 242,871 more on the Live Register than in May 2007," said Willie Penrose, Labour's Enterprise, Trade and Employment spokesman.
"Those of us who lived through the 1980s hoped that we would never again see such numbers on the Live Register; now we are seeing figures of more than 100,000 greater than anything seen in the worst days of the 1980s.
"If the government continues to ignore the unemployment crisis the country will continue to not just suffer economic damage, but also face the prospect of long term unemployment doing untold social damage to communities all over the country," he added.
The Irish Congress of Trade unions (Ictu) said soaring unemployment figures were a clear indictment of failed Government polices and it reiterated its call for a €1 billion job creation and protection plan.
“The severity of this crisis requires the same intense focus and attention as the Banking Crisis has received. Broken banks can be fixed, it is much harder to repair lives broken by unemployment and lack of opportunity,” said Congress economic advisor Paul Sweeney.
On a more positive note, Alan McQuaid, chief economist at Bloxhams noted that the monthly jump was far lower than the rises of 33,000 in January, 26,700 in February, 20,000 in March and 15,800 in April, suggesting that the absolute rate of increase is on a declining trend.
"While the fall-off in labour force growth will somewhat dilute the impact of contracting employment on the jobless rate, the numbers of unemployed are still set to rise sharply this year. But, it now looks like the Live Register won’t hit the 500,000 mark in 2009, with the figure signing on at year-end set to be around 470,000 or 13.8 per cent of the workforce," said Mr McQuaid.
Employers group Ibec also noted the slowing pace of job losses. Nonetheless, it said that redundancies in the first five months of the year are 166 per cent higher than in 2008 and called on the Government to introduce supports for enterprise to minimise job losses.