The leu opened at 4.340/4.342 against the euro, compared to 4.332/4.334 at closing the day before.
Within the first hour, the leu continued to weaken and, at around 10:10 local time it was trading at 4.345/4.3480 against the European coin.
The central bank published Monday a leu-to-euro reference of 4.3243 units, compared to the previous reference of 4.315 units.
On the money market, overnight rates rose to 5.5%-6% a year, from 5.3%-5.8% a year previously.