PARIS, April 2 (Reuters) - Goldman Sachs told its Paris staff they could work remotely on Thursday following a foiled ‌bomb attack on Bank of America Paris offices last ‌Saturday, a source familiar with the matter said, while Citigroup staff in Paris and ​Frankfurt are also working remotely.

French authorities have placed four suspects in pre-trial detention over the plot, which potentially had links to Iran.

The Paris police authority did not immediately reply to a request seeking comment, ‌while the Paris prosecutor's ⁠office declined to comment.

Citigroup's is a precautionary measure, the group said in an emailed statement to Reuters.

French anti-terrorism ⁠prosecutors said late on Wednesday the four suspects — three teenagers aged 16 and 17 and one adult — were placed under formal investigation on ​suspicion of ​manufacturing, transporting and handling an ​explosive device and attempting to ‌destroy property as part of a terrorist organisation.

The device, a five-litre petrol can taped to a large pyrotechnic charge containing a 650-gram active-material cylinder, was the most powerful of its kind ever identified in France and could have generated "a powerful fireball several meters in ‌diameter," the anti-terrorism prosecutor's office said ​late on Wednesday.

Investigators established the adult recruited ​the teenagers, paying them ​between 500 and 1,000 euros ($580-$1,160) to plant and ‌film the device. All four denied ​terrorist intent.

France suspects ​the attack is linked to HAYI, a pro-Iranian group that had posted a video on March 23 specifically naming Bank ​of America's Paris ‌headquarters, though prosecutors said the link has not yet been ​formally established.

(Reporting by Anousha Sakoui and Mathieu Rosemain. Editing ​by Inti Landauro and Jane Merriman)