MADRID – Authorities in Spain released a video Saturday that they claim shows suspected al-Qaida members training for a bombing raid using a model plane, the latest development in a case that led to three arrests.

Spanish officials allege the suspects were planning a terrorist attack in Spain or elsewhere in Europe, but say investigators intercepted them before they could carry out their plot.

The undated video clip — grainy and of low quality — shows a colorful model propeller plane noisily taking off.

Once airborne, it drops a small object that falls to the ground and a man then runs toward where the object landed. The identity of the man is not clear.

Two of the arrested suspects are Russians of Chechen descent — Eldar Magomedov and Mohamed Ankari Adamov. They were jailed Aug. 5 on provisional charges of belonging to a terrorist organization.

The third man, a Turk named Cengiz Yalcin, was also jailed on provisional charges of possession of explosives and a device likely to be used in a terror attack.

Spain’s Interior Ministry also released photographs of an underground space uncovered by police at Yalcin’s home in the southwestern city of La Linea where investigators discovered around 5.3 ounces of an allegedly explosive substance.

Judge Pablo Ruz of the National Court, who jailed the three suspects, described Yalcin as an engineer who had worked in Gibraltar for years and had been involved in providing paragliding lessons for the Russians.

Ruz also said in a court statement that evidence from the U.S. Justice Department suggested that Magomedov was involved in terrorist activity in 2010 in Afghanistan and Waziristan, a lawless tribal territory in Pakistan, known as a militant hotspot.

It was not clear whether the three had attorneys.