The European Union will raise 6 billion euros ($6.6 billion) from the sale of a new, 20-year green bond on Tuesday, memos from two lead managers seen by Reuters showed.

The green bond will fund member states' environmentally friendly projects that are part of the bloc's COVID-19 recovery fund.

The bond, due on Feb. 4, 2043, saw final investor demand of over 78.25 billion euros, one of the lead managers said.

It will pay a spread of 9 basis points over the mid-swap level, down from around 11 basis points when the sale started, the lead managers said.

Demand was higher than in recent EU debt sales. Demand is usually higher for green bonds compared with regular issues, as a dedicated investor base chases a limited supply.

Tuesday's issuance is the EU's second green bond following a debut issue last October. That saw record demand and was the largest ever green bond sale, raising 12 billion euros.

The EU is expected to eventually become the biggest issuer of green bonds globally. It aims for 30% of the up-to 800 billion euro recovery scheme, which gives grants and loans to member states until end-2026, to finance environmentally beneficial projects that the EU will fund with green bond issues.

The EU hired BofA, Citi, Credit Agricole, Danske Bank and JPMorgan for the sale for the syndicated debt sale on Monday.

($1 = 0.9106 euros)

(Reporting by Yoruk Bahceli; editing by Sujata Rao and Barbara Lewis)