Test drilling at the Leviathan 1 undersea oil field off the Haifa coast was halted on Wednesday before reaching the target depth because of technical difficulties, Israel Radio reported.

The field, estimated to hold 450 billion cubic meters of natural gas, is a linchpin in Israel’s quest for energy independence, especially as gas supplies from Egypt have become unstable

Egypt recently announced it would stop providing Israel with gas, a move that followed a dozen attacks within the past year on the gas pipeline in Sinai, which decreased the flow of gas eastward to a trickle.

The companies managing the Leviathan site, Noble Energy, Ratio Oil Exploration, Delek Drilling, and Avner Oil & Gas Exploration, said high pressures and technical and mechanical limitations prompted the halt.

Drilling stopped 6,500 meters below sea level, the deepest ever excavated in the eastern Mediterranean.

In the coming months Noble Energy will check the drilling statistics in order to reestimate the field’s potential and consider drilling deeper using a more appropriate rig for deeper depths.

The Lower Oligocene rock the drilling reached showed no signs of natural gas, but the likelihood of finding gas at that depth were considered slim at the start.

Drilling has cost the partner companies $270 million.