Cases of deliberate fire raising in Tayside and Fife have increased by almost 20% in the past three years.
The number of incidents went up from 1,559 in 2015/16 to 1,743 in 2016/17 and 1,860 in the year to April.
In Dundee, cases hit a three-year high of 739 last year, compared to 615 in 2015-16.
Campaigners fear tinderbox conditions after the long, hit dry summer could lead to incidents getting out of control and have urged communities to keep an eye out for potential firebugs.
North East Conservative MSP Bill Bowman said: “The act of starting a malicious fire is worse than reprehensible.
“With the hot and dry weather of the past few weeks, the wrong action can have heartbreaking consequences.
“Once a fire starts you have lost control. A match in the wrong hands is as deadly as any weapon.”
It emerged last year that the operational role of the Scottish Fire and Rescue Service would be drastically changing because, the service said, fewer fires are being dealt with across the country.
The closure of some stations was floated, as was reducing the number of firefighters, while those on the front line would take on an increased role responding to terrorist incidents, helping elderly people in the community and assisting with medical emergencies.
The most recent set of official statistics show that, in 2016/17, SFRS attended a total of 91,139 incidents, an increase of 2,254 on 2015/16.
And the number of malicious blazes being set has gone up in every local authority area across Tayside and Fife, with the exception of Perth and Kinross.
Angus witnessed 145 cases of deliberate fire-raising in the year to April, compared to 103 in 2016/17 and 117 the year before.
There were 707 incidents in Fife in 2015/16, which went up to 761 the following year and 860 in 2017/18.
In Perth and Kinross the number of cases fell slightly from 120 in 2015/16, to 112 in 2016/17 and 116 in the year to April.
Senior officer for Dundee, Angus, Perth and Kinross Gordon Pryde said: “The Scottish Fire and Rescue Service has a very clear, zero tolerance approach to deliberate fire raising because it puts our communities at great risk.
“It presents a danger to life, property and the environment – not to mention the potential impact on businesses which are important to the economy.
“We work to educate members of the public on the very real dangers of fire-setting and try to lay bare the fact that every deliberate fire has victims, costs – and consequences.
“We will continue to work very closely with our police and local authority partners to ensure that those responsible are identified and dealt with accordingly.”