A suspected underground Iranian nuclear site has seen a surge in construction this year, according to AFP reports citing a review of satellite imagery published by US analysts.

The deeply buried site at Pickaxe Mountain is near Natanz, where Western intelligence suspects Iran is building an undeclared enrichment facility.

Analysts at the Centre for Strategic and International Studies (CSIS), a Washington-based think tank, have reviewed satellite imagery spanning six years, with the latest imagery from today.

“Together, these images reveal more road activity at Pickaxe Mountain in 2026 than at any point in the site’s history,” the CSIS analysts write.

“There is a clear surge in construction activity in 2026 that corresponds to the raising and hardening of the portal accesses, paving of the internal road network, reinforcement around access areas, and the flattening and removal of excavation spoil,” the analysis adds.

However, the analysts say they cannot refute or substantiate a reported Israeli intelligence claim that Iran has moved centrifuges into Pickaxe Mountain.