Hikers in the Dolomites in northern Italy said they were frightened after a glacier collapsed at the weekend, killing at least seven people in a tragedy experts linked to rising temperatures.

"Right now after what happened I feel a bit scared because two days ago we were about to walk just near the glacier. It could have happened to us," said Mikael Bouchard, a 29-year-old from Lyon.

"We were planning to go near the glacier but right now we are going to do another way (route) to avoid it. So yeah, it's really scary," added Bouchard, who was walking lower down the mountain.

Rescue teams resumed the search on Tuesday for 13 climbers who were still missing almost two days after part of a glacier gave way on the Marmolada, which at more than 3,300 metres (10,830 ft) is the highest peak in the Dolomites.

Canadian tourist Oscar Wong, who lives in Seattle, said he would continue his trip but try to be aware of the dangers.

"Certainly I think the risks are elevated.. (and) have to take that into consideration when I'm planning my routes," the 28 year-old said.

A huge mass of ice collapsed close to Punta Rocca, on the route usually used by hikers and climbers to reach the summit, the Alpine rescue unit said.

Temperatures on the normally freezing Marmolada had reportedly touched 10 degrees Celsius (50 Fahrenheit) over the weekend. Scientists said rising temperatures were making glaciers more unstable.

"I've never heard of something like this happening, especially in the summertime in July, especially in this region so it's definitely a surprise to me," added Wong.

(Writing by Emily Roe and Keith Weir, Editing by Alexandra Hudson)