The Serious Fraud Office (SFO) is questioning former traders from Barclays and Deutsche Bank over possible Euribor rigging.

According to the FT, which spoke to sources close to the matter , they are being interviewed “under caution”. This means the UK fraud investigators must have at least a reasonable suspicion of wrongdoing, and this type of questioning is usually the stage before final decisions are made about whether to charge.

Euribor, which is the European equivalent of Libor, is a key borrowing benchmark calculated using submissions from a panel of 25 banks. The number involved used to be higher, but many banks were cut in light of the Libor scandal.

It is possible that individual traders rigged their submissions to make personal financial gains, and this led to an investigation being launched in July 2012. The SFO said the enquiry was “in relation to the alleged manipulation of Libor and related interest rates”.

So far, the European Commission has charged seven banks for alleged manipulation of the benchmark.