Germany, Czechia, Poland and Hungary reached record temperatures of more than 40C on Sunday as a heatwave linked to hundreds of deaths in western Europe spread east.

More than 191 million people in Europe faced temperatures of at least 35C, with extreme heat warnings across the region.

Germany recorded a new all-time high of 41.7C, in Coschen, near the Polish border in eastern Brandenburg, according to preliminary data from the national weather service. This broke the previous record of 41.5C set a day earlier in Drewitz.

In Gohrischheide, in eastern Germany, a fire broke out in a forest contaminated with ammunition from the second world war, complicating firefighters’ efforts.

A major firefighting operation was also paused at a former munitions disposal site near the village of Traisen in south-west Germany.

Firefighters had to briefly pause after explosions were triggered and a bomb disposal unit was brought in, the German news agency DPA reported.

About 650 people in Traisen had to leave their homes on Sunday because the fire continued to spread.

In Berlin, police sprayed water cannon into the air to help residents and tourists cool off. The German rail operator Deutsche Bahn advised against all nonessential travel.

Poland surpassed its all-time heat record with temperatures reaching 40.5C in Słubice, on the Polish-German border, breaking a 105-year record of 40.2C, set in 1921.

The Polish government’s security agency sent out text messages urging people to “avoid the sun and strenuous activity”, drink water and wear hats throughout the weekend. Multiple cities set up water curtains to help residents keep cool in the heat.

Hungary also broke its all-time record, with 40.7C reported in Budakalász, higher than Saturday’s 40.0C and the country’s previous record of 37.5C from 1994.

Czechia also reported a new all-time high of 41.9C in Doksany, confirmed by its hydrometeorological institute on early Sunday afternoon. “Temperatures continue to rise, this is not the final maximum,” it said in a statement.

In Slovakia, 39.3C was reported in Mužla, in the south-west of the country.

Denmark had on Saturday registered its highest temperature since measurements began in 1874, with 36.6C north of Odense.

Meanwhile, France has begun counting the deaths caused by its heatwave.

The French national public health agency said that between 24 and 27 June, 1,000 additional deaths were recorded compared with figures in previous months. These figures were provisional and were expected to rise significantly.

The sharpest increase in deaths related to people dying at home, particularly in the Île-de-France region that includes Paris and its suburbs. The majority of deaths were among people over 65, but younger people were also affected.

“This serves as a reminder of the need for measures of solidarity towards people who are isolated or experiencing profound loneliness, including in highly urbanised areas,” the health agency said in a statement.

Philippe Juvin, an emergency doctor and MP for the rightwing Les Républicains party, said the final death toll in France would be very high. He said on Sunday there were likely to be people still in their homes in a coma, or who had died, who might not be discovered until next week.

The French prime minister, Sébastien Lecornu, said hospitals and emergency services would remain under pressure for the coming days.

Marine Tondelier, the leader of the Greens, said “all light must be shed” on the “very high death toll” and political conclusions must be taken for action on the climate crisis.

The French interior minister, Laurent Nuñez, said ambulance services responded to more than 122,000 callouts during the hottest period of the heatwave.

Preliminary figures in Spain showed at least 327 deaths that could be linked to the heat between last Sunday and Thursday.

A large part of northern France was also hit by violent electrical storms and high winds, which caused several injuries, as emergency services attended to fallen trees on roads and flooded homes.

Lightning in the Aisne area sparked several fires, including one in Laon, where five people were injured. Storms caused electricity outages, and more than 60,000 homes were without electricity on Sunday morning.

One man died in Belgium when a tree fell on his vehicle outside Brussels, media said, after violent storms hit much of the country.