The level of arson attacks in the UK rocketed by 20% in 1999, according to the latest figures from the Home Office.
But the cost to the insurance industry has barely risen. So far, the bill is £434m compared to 1998's overall figure of £432m.
The government's latest figures show that there were over 100,000 attacks in 1999.
Malicious vehicle fires are the biggest problem rising by a third to 60,000 last year.
Arson Prevention Bureau chief executive Chris Mounsey said: “Arson is a major social and economic problem, which causes loss of life, serious injuries and hundreds of millions of pounds worth of damage to all types of property.
“These worrying new figures highlight that the £3.5m recently announced by the government in support of the forum is much needed.”