Thailand's Finance Ministry adjusted the country's gross domestic product (GDP) forecast for the year from 4 percent to 3.7 percent, Thai News Agency reported on Saturday.

Somchai Sujjapongse, director of the Fiscal Policy Office, said this year's GDP would not reach 4 percent unless the government speeds up its 2014 budget spending.

A budget of $2.75 billion from a total of $19.20 billion must be injected into the system before the end of this year, he said.

The ministry also predicted a 5.1 percent growth next year due to a planed infrastructure development investment, which amounts to $64 billion, he added.