Thailand on Monday posted its fastest quarter of economic growth in three years of junta rule, a boost for a country that was once Southeast Asia's economic dynamo but has labored under years of political upheaval. 

Since toppling the civilian government in May 2014 the ruling junta has struggled to fulfill its promise to kickstart the economy.

High household debt and slumping consumer spending has chipped away at growth, while a year-long national mourning period for the late Thai king also depressed the economy.   

But on Monday the Office of the National Economic and Social Development Board delivered some good news, saying GDP accelerated by 4.3 percent in the three months to September compared with the same period last year.

As a result the board raised its full-year growth forecast from 3.5 to 4.0 percent.

It welcomed a junta pledge to hold elections next year "which will boost investor confidence... particularly among foreign investors".

An analysis note from Goldman Sachs welcomed the better-than-expected figures but cautioned that the economic recovery was heavily weighted on exports and "has not been broad-based".

Thailand has seen two coups and several short-lived civilian governments since 2006.