Transport Secretary Heidi Alexander said that there would be an enhanced "high visibility presence of officers at stations and on trains" throughout today, to "reassure the public".
The increased police presence will likely concentrate on major rail terminals such as London, Birmingham, York, Leeds and Manchester – as well as Huntingdon, where forensic officers continue to scour the train on which the attack took place.
There will also be a visible police presence on trains on the East Coast mainline.
Officers are likely to be most visible across London and in Huntingdon, a PA report stated.
While officers usually focus on stations, the sources told PA it was "important to reassure passengers".
Although terrorism has been ruled out, police are still working on uncovering the motive for the attacks and have insisted that "at this early stage it would not be appropriate to speculate on the causes of the incident".
Two men are currently being held in custody on suspicion of attempted murder; they are a 32-year-old black British national and a 35-year-old British national of Caribbean descent, police said.
The LNER Azuma train remains at Huntingdon Station, frozen in place following the mass stabbing on Saturday night.
Train operator LNER says there will be disruption between London King's Cross and Peterborough until the end of Monday, with no trains stopping at Huntingdon during that time.
