Inflows were 589 million euros, mainly representing changes in credit institutions' foreign currency-denominated required reserves, inflows into the finance ministry's accounts and inflows into the European Commission's account.
Outflows totalled 1.776 billion euros and reflected changes in credit institutions' foreign currency required reserves.
It said interest payments and principal repayments on foreign currency public debt amounted to 1.416 billion euros, of which principal repayments and interest payments on the European Commission's loan granted to the finance ministry in 2009 was 1.239 billion.
The central bank said payments to service external public and publicly guaranteed foreign currency debt in May amounted to 157 million euros.