* S/adj adjusted rate at 4 pct, highest since May, 1998
* Unadjusted rate at 3.8 pct, highest since Jan, 2006
ZURICH, Sept 8 (Reuters) - The deep recession pushed Switzerland's unemployment rate to its highest level in more than a decade in August, sending a staunch reminder that the economy may face a bumpy road to recovery.
Unemployment rose to 4.0 percent when adjusted for seasonal swings from 3.9 percent in June, the State Secretariat for Economic Affairs (SECO) said on Tuesday.
This was the highest since May 1998 and in line with economists' expectations in a Reuters survey.
The unadjusted rate also ticked up to 3.8 percent in August, with the total number of jobless rising to 150,831. At the same time, the number of vacancies fell to 13,353.
Signs have been mounting over recent weeks that the Alpine economy may be about to move out of its worst recession in decades.
But Swiss National Bank board member Thomas Jordan warned two weeks ago that the recovery could take time and the unemployment rate may rise to a nearly 6 percent next year -- a post-war record.