Robbers drilled through the back portion of a jewellery shop and carted away jewellery worth RM1 million in Jalan Genting Klang on Saturday.

The robbery was believed to have taken place at 9pm on Saturday and was only discovered by the shop's employee at 8pm on Sunday.

Sentul District Assistant Police Chief Supt Othman Abu Bakar said the gang was believed to monitored the activities at the premise for some time and has the expertise to break through walls and vaults.

"We believe they used the oxy-acetylene blow torch to cut through the vaults," he said.

Othman said the gang had also cut off the alarm system and close circuit camera (CCTV) cables installed at the premises.

A female employee of a nearby shop said the robbers had also shifted the CCTV at the back of the premise, during the robbery.

A visit to the shop by Bernama found a human sized hole at the back of the premise while the grille inside had been broken while drilling marks were found on the wall leading to the jewellery vaults.