The leu opened at 4.5035/4.5065 to the euro, weaker than 4.501/4.5035 to the euro at Wednesday closing.
It slided even further in the first hour of the session, and traded at 4.5075/4.5090 units at around 10:15 local time (GMT0715).
Other currencies in the region were losing up to 0.9% against the euro.
Dealers said investors have tried several times to bring the leu over 4.51 units but any attempt was counterbalanced by hard currency selling orders that brought the leu under this threshold.
The central bank Thursday set the leu’s reference at 4.5037 against the euro, slightly weaker on the day. Against the US dollar, the leu’s indicative lost 0.3% to 3.4604 units.
On the money market Thursday morning, overnight rates decreased at 1%-2% a year, amid liquidity surplus.