The institute said further exhumation work planned for spring 2027 would allow researchers to establish more precisely the age, sex and cause of death of those buried there.
On the final day of the search, investigators dug test trenches and partially exposed one mass grave containing the remains of eight people, the institute said.
The search began on 6 October and was conducted as part of arrangements agreed by a Polish-Ukrainian working group on dignified burials.
The Polish Institute of National Remembrance (IPN) had two observers present during the work, its spokesman Rafał Kościański told PAP, under administrative decisions issued by the regional heritage protection office.
The UINP cited historical sources saying more than 300 Ukrainians were killed in a mass killing in Łasków on 10 March 1944.
The institute said Ukrainian and Polish historians and experts had established details of 327 Łasków residents who died in 1944, while some historians estimate the death toll at around 350. It said further research might establish the final number.
Last week, the UINP reported that the remains of around 30 people had been found. It said the Ukrainians in Łasków had died following attacks by units of the Polish Home Army (Armia Krajowa) and Peasants' Battalions (Bataliony Chłopskie) in March 1944.
(sp)
Source: PAP