The establishment belonging to the ZT Hotels chain in May snubbed the group from Tarancón in Spain's Castile–La Mancha region.
The group were turned away from the hotel in the Valencian coastal town of Peñíscola because of fears members would become aggressive, the director of Cuenca Disabled Forum Enrique Alarcón told Valencia's online news site Diario Crítico in May.
The hotel said it had experienced similar problems before, Alarcón explained.
Now, the case is moving ahead with regional authorities in Castile–La Mancha having asked authorities in Castellón to investigate whether a crime was committed.
Spain's Secretary for Health and Social Affairs José Ignacio Echániz presented the petition to Castellón in a case which has gone all the way to the top.
"We have to be tough against this type of discrimination because we can't tolerate it happening again," said the health secretary.
Echániz said his office would give his full support to the group in the case.
The ZT Hotels chain also came under fire in May when its Hotel CaboGata Plaza Suites in Almeria turned away a group of children with Down's Syndrome.
The hotel said "these kinds of people might annoy other guests".
Sources from the hotel later apologized to Spain's Down's syndrome association Down España, saying that the incident had been "a misunderstanding".
They claimed that hotel staff had believed they were dealing with a group of former hotel guests with a different mental disability whose visit had been "very confrontational".