BEIJING (Reuters) - More than two thirds of the companies investigated by China in its latest campaign against pollution have violated environmental rules, a environment ministry official told a briefing on Friday.

China launched a campaign earlier this month aimed at “normalising compliance” in 28 cities in the Beijing-Tianjin-Hebei region, a major pollution hotspot.

Tian Weiyong, head of the monitoring department at the Ministry of Environmental Protection (MEP), said 4,077 firms had already been investigated as part of the campaign, and 2,808 firms were found to have violated environmental rules, 69 percent of the total.

China is in the fourth year of its “war on pollution”, but the Ministry of Environmental Protection (MEP) has traditionally struggled to impose its will on powerful industrial enterprises and growth-obsessed local governments.

It has drawn up new laws and standards, increased the range of punishments and boosted its monitoring and enforcement capabilities in order to tackle non-compliance.

China imposed total fines of 6.63 billion yuan ($963.30 million)for environmental violations in 2016, up 56 percent compared to the previous year, the environment ministry said in a statement ahead of the Friday briefing.

It said it punished a total of 137,800 environmental violations in 2016, up 34 percent from 2015, in its efforts to boost environmental law enforcement and compliance.

The Beijing-Tianjin-Hebei region is under pressure to cut 2012 levels of breathable particulate matter known as PM2.5 by a quarter by the end of this year.

While the region has made progress over the past five years, average PM2.5 concentrations in the region rose 48 percent year-on-year in the first two months of 2017.

Friday’s statement said China now had a workforce of more than 70,000 responsible for enforcing environmental laws and regulations, and noted the MEP was also encouraging ordinary citizens to report pollution.

In a separate statement on Friday, the Beijing environmental protection bureau issued new guidelines, saying it would pay rewards up to 50,000 yuan to residents who reported serious environmental violations, including the dumping of hazardous waste or radioactive materials.

Individuals who report firms for improperly using or tampering with environmental monitoring equipment could get a 3,000 yuan reward, the environmental protection bureau said.

($1 = 6.8826 yuan)