The military wing of Hamas opened its Gaza summer camp on Saturday, aimed at providing basic combat training for 25,000 Palestinians in the embattled strip.

Hamas, the de facto power in Gaza, is currently engaged in indirect contacts with Israel to try to reach a long-term truce, but a year after last summer's devastating 50-day war the movement has kept up the fighting talk.

"The goal of these military training camps is to train the vanguard for liberation -- spiritually, intellectually and physically -- to be ready and able to play its role in liberation," said a statement by the Ezzedine al-Qassam Brigades, Hamas' military wing.

It said that participants, aged 15-60, would spend two weeks being "trained in military techniques and in firing live ammunition" as well as "first aid and rescue techniques."

As with all the brigades' activities the camps will be conducted out of public and media sight.

Rescue squads dealt with thousands of local victims during the offensive of July-Agust 2014, the third in Gaza in six years.

Hamas has long run summer camps devoted to sport and study of the Koran in Gaza but over the winter the al-Qassam brigades launched a new kind of camp, giving military training to 15 to 20-year-olds.

Human rights activists condemned it as a forced militarisation of Gazan society and a violation of children's rights.

Brushing off the criticism, the brigades are repeating the excercise with the summer camp, while raising the upper age limit to 60.