The measure will make it possible to use state reserve funds for dealing with the landslide problems.
Gediminas Hill and the remains of the Upper Castle complex are currently in a dangerous condition, the capital's local authority said in a press release.
"Linear deformations in the southeastern slope may merge in the near future to cause an even greater landslide than the one that occurred on the northwestern flank last October, and this could lead to the collapse of the remains of the Upper Castle," it said.
Works are already underway to reinforce the hill's northeastern slope, with 2.9 million euros allocated for this purpose. Experts warn that the southeastern slope is also under risk. It is estimated that another 5 million euros or more may be needed to fix this part of the mound.