FRANKFURT, Germany — Eight of 90 banks have flunked stress tests that project how they would fare in another recession, and 16 more barely passed, Europe’s banking regulator said Friday.

The failing banks should “promptly” take steps to strengthen their financial cushions against losses, the European Banking Authority said as it released the results. They now have to raise a total of $3.5 billion.

Spain, whose many local savings banks have been closely watch by analysts, fared worst, with five banks failing to prove that their capital buffers were strong enough to sustain the regulator’s stress scenario. The banks were Catalunya Caixa, Caja de Ahorros de Mediterraneo, Banco Pastor, Unnim and Grupo Caja.

Two Greek banks, EFG Eurobank and ATEBank, also flunked, as did Austria’s Oesterreichische Volksbank AG.

The banks that barely passed have been asked to strengthen their finances along with the ones that failed.

The EBA lacks the power, however, to force banks to raise more capital — whether from investors or governments — or to make them merge or sell businesses.