LIMA (AFP) - Rescue workers in Peru have mounted an intense search to find two Italian mountain climbers who disappeared four days ago while trying to reach one of the country's highest peaks in the Andes.

"They were heading to the summit when a ledge broke off in the zone of the northeast face" of the 5,947m Alpamayo mountain, rescue team chief Alfredo Quintanilla said on Tuesday.

He said the high-altitude search team includes around 10 rescue workers in two groups working in coordination with police.

The effort to find the two missing climbers, both in their 20s, has been under way since Saturday, when two other Italian climbers from their group alerted the authorities to their disappearance.

The search is being conducted on the ground and from the air with the help of a police helicopter, but there was no sign of the two men. Poor weather has hindered rescue efforts.

Alpamayo features a daunting slope that renders an ascent particularly challenging, as well as pyramids of ice that have prompted the nickname among locals of "the most beautiful mountain in the world".

It is part of Peru's Cordillera Blanca, or "White Range", which stretches for 180km and includes numerous peaks that are 6,000m or higher.