AUGUSTA (AP) – Maine’s unemployment rate rose by 0.7 of a percentage point in May to 5.4 percent, Maine’s highest rate in more than a decade, the state Labor Department said Friday.

Labor Commissioner Laura Fortman said last month’s increase was “unusually large,” adding that several more months of data will be needed to see if a trend develops. A spokesman for Gov. John Baldacci called the increase “alarming.”

“We hope to see the numbers correct themselves in the months ahead,” said spokesman David Farmer.

State Labor Department officials said the April-to-May increase was due in part to the sagging national economy. But part of the rise is also due to a statistical fluke tied to the timing of unemployment data gathering, said the department’s Dana Evans.

Jobless rates were measured the week after many college students finished their work-study jobs for the academic year, but before they started summer jobs, causing a bump in the jobless rate, Evans explained. Normally, the numbers come in before work-study ends.

Maine’s unemployment rate was a shade better than May’s national rate of 5.5 percent, the department said. But it was also Maine’s highest rate since April 1997, according to figures provided by Evans.

Officials weren’t sure of the significance of those figures, but said the national economy’s influence on the state’s ups and downs can’t be discounted. That is especially true as Maine businesses become more deeply involved in a global economy, said Farmer.

Labor officials said Maine’s unemployment rate also rose from 4.7 percent in May 2007 to 5.4 percent in May 2008. Over that period, jobs in service-sector fields such as health care and hospitality recorded gains, while manufacturing positions shrank, reflecting Maine’s shift from a manufacturing to service-based economy.

Maine’s jobless rate in May was among the highest in New England, the Labor Department said. Rhode Island’s seasonally adjusted rate was the highest at 7.2 percent, followed by Maine and Connecticut at 5.4 percent. Massachusetts recorded 4.9 percent and New Hampshire 4 percent. Vermont figures were unavailable.

Maine county jobless rates, unlike those for the whole state, are not seasonally adjusted. The highest unemployment rates for May were in Piscataquis and Washington counties, 9.5 percent and 9.3 percent respectively, while the lowest were in Cumberland and York counties, 3.9 percent and 4.2 percent.