Bus firm Stagecoach has said there is no connection between the fires that have turned a series of their vehicles in Tayside into smouldering wrecks.
Four Stagecoach buses have caught fire in Dundee and Angus over the last nine months, as did a National Express coach.
The most recent incident was on Friday, when a Stagecoach bus went up in flames at a bus stop by the Fowlis junction on the A90 Dundee to Perth road, just minutes after dropping off a group of children.
Less than a week earlier, a suspected electrical fault caused the number 20 bus from Kirriemuir to Dundee to catch fire.
Last September, another two Stagecoach buses caught fire within a week of each other.
Dozens of passengers were on a bus in Monifieth when it caught fire on September 15.
Three days later, another bus caught fire near Letham. It burned with such intensity that the road was damaged.
A National Express coach caught fire in Dundee in March and dozens of passengers had to flee.
No passengers have been injured in any incident.
A Stagecoach spokeswoman said, “The safety of our passengers and staff is our highest priority.
“As you would expect, we are carrying out a thorough investigation into these incidents, which has so far established that the causes were completely unrelated.”
She added, “All of our vehicles undergo an extremely strict maintenance regime, beyond standards set by the bus industry and in both cases our drivers demonstrated their competence and professionalism by ensuring that no passengers, or other road users, came to any harm.”