"The NBH is committed to buy green government bonds as part of its asset purchase programme under similar conditions than any other government bond," the bank said.
The Hungarian forint firmed 0.21% and was trading at 363.95 per euro, extending its gains since Tuesday when the central bank left interest rates unchanged.
"The NBH was so convincing that the forint firmed this week despite the strengthening of the dollar," one trader said.
*It bought 16 billion forints worth of 2033/A bonds at 2.32% average yield, 3 billion forints worth of 2034/A bonds at 2.48%, 4 billion forints worth of 2038/A bonds at 2.8% average yield and 2 billion forints worth of 2041/A bonds at 3.05%.
It bought 8 billion forints worth of 2031/A bonds at 2.13% average yield, 7 billion forints worth of 2038/A bonds at 2.45% average yield and 4 billion forints worth of 2041/A bonds at 2.75%.
The National Bank of Hungary (NBH) has said it would hold foreign currency swap tenders at the end of each quarter if needed to reduce market volatility.
By providing euros via fx swaps, the NBH can ease selling pressure on the forint on the spot market.