A number of Virgin's flagship Voyager trains are undergoing checks after one separated into two sections in Devon on Sunday.
The train was travelling between Newton Abbot and Teignmouth
A Virgin service from Penzance to Glasgow, made up of two connected Voyagers, split while travelling between Newton Abbot and Teignmouth.
No one was hurt but passengers were left stranded for two hours.
Virgin Trains spokesman David Ewart said there was "no compromise of passenger safety whatsoever".
The rail operator has already examined the end couplings of all 78 trains in
its 125mph Voyager fleet following the incident.
Virgin said on Tuesday several of the trains' couplings "warranted further investigation" and will not be joined together with other Voyagers until checks have been completed.
The incident caused disruption to other services on Sunday afternoon while the trains were recovered.
Mr Ewart said: "No-one was in any danger, but people were marooned on the train for a couple of hours.
"We carried out the normal full fleet examination and found a very small number of couplings that we felt warranted further investigation. That is being
Mr Ewart said all Virgin services were continuing to run as normal.