Israeli armed forces have started to fill up Hamas' tunnels in Gaza with seawater, The Wall Street Journal reported on Tuesday citing United States officials with knowledge on the matter.

According to US officials, Israel is still evaluating the utility of using seawater in underground passages that are around 300 miles long and have thick blast doors. The water being used comes from the Mediterranean Sea.

The US officials added that the process is expected to last for weeks and is only one of the ways Israelis are trying to destroy the tunnels. Israeli officials have been saying that these underground corridors have been of utmost importance to Hamas and its operations.