Egypt discovered and destroyed 12 smuggling tunnels linking the Gaza Strip to the Sinai Peninsula, the Egyptian army said Monday.

Egyptian army spokesman Tamer al-Rifae said that the tunnels, in the north of the Sinai, had been destroyed, though he did not specify when the demolitions were carried out.

Earlier Monday, Hamas published a report in which it said that it had lost 21 members of its armed forces while digging tunnels under the Gaza Strip in 2016, some of them to Egypt and some into Israel.

Last month, four men, aged 22 to 45, were killed when the Egyptian army flooded a tunnel with seawater. The men were found dead 9 days after the tunnel they had been working in was flooded by the Egyptian army, according to a statement by local authorities in the Gazan city of Rafah near Egypt’s border.

Gazans use such tunnels to smuggle goods and weapons into the Palestinian enclave that has been under Israeli and Egyptian blockade for a decade, following Hamas’s violent takeover of the Gaza Strip and its use of the area as a launchpad for attacks on Israel.

It is also a conduit for Islamic terrorists who are operating in the Sinai, against Egyptian forces.

Israel says the blockade is required to keep arms and materials that can be used for war-making out of the hands of Hamas and other terror groups in Gaza.

Under President Abdel-Fattah el-Sissi, the former military chief who ousted Morsi, Egypt all but destroyed a once-thriving network of cross-border smuggling tunnels used by Hamas — robbing the group of its main economic lifeline and a key source of weapons.

Targeting Islamic militant groups in Egypt’s northern Sinai Desert, it also destroyed hundreds of homes in the volatile border area to create a “sterile zone.” Egypt’s state-run media have repeatedly accused Hamas of collaborating with militants in Egypt, a charge the group denies.

In recent months, however, Cairo has increased the number of people allowed to exit through the Rafah border crossing, Gaza’s main gateway to the outside world. It also has begun to allow Gaza to import commercial goods through Rafah for the first time since 2013, and has sent public signals that it is interested in improving relations.

Agencies contributed to this report.