"The captain who headed the company has been suspended and an investigation has been opened," the army said in a statement to AFP, without giving further details nor saying whether the move was temporary or permanent.

A group of soldiers angered by the gesture published footage of it on the "Citizens in Uniform" Telegram account, denouncing it as "a shameful video".

In the footage, several dozen of soldiers, one carrying the company's flag, can be seen kneeing on the stone steps in front of the late dictator's former mausoleum outside Madrid.

A few steps up stands a priest in a white cassock who reads a blessing.

"Citizens in Uniform" said the captain had organised a march to the Valley of the Fallen, 50 kilometres (30 miles) outside Madrid, "with the idea of having the company's flag blessed at the basilica".

They said he had cancelled all leave for that particular day and required that all company members attend.

The imposing basilica is part of what used to be a grandiose hillside mausoleum topped by a 150-metre (500-foot) cross where Franco was buried after his death in 1975.

It is a deeply divisive symbol of a past that Spain still finds difficult to digest.

In October 2019, Franco's body was exhumed and moved to a more discreet grave in a carefully-choreographed operation led by Spain's left-wing government.

Built by Franco's regime after the 1936-1939 civil war -- in part by the forced labour of some 20,000 political prisoners -- the site contains the remains of more than 33,000 dead from both sides of the civil war.

It has long been a draw for those nostalgic for the Franco era, who used to hold masses in his honour and celebrate his memory.

The exhumation was strongly opposed by the dictator's living relatives as well as by the prior of the Benedictine monks who manage the site.