BERLIN (Reuters) - The German Defense Ministry will notify lawmakers shortly that it will proceed with plans to lease Israeli-built Heron-TP surveillance drones, a program that was delayed last year, Defense Minister Ursula von der Leyen told top military officers on Monday.

Defence Minister Ursula von der Leyen walks at the German government guesthouse Meseberg Palace in Meseberg, Germany, April 11, 2018. REUTERS/Fabrizio Bensch

The ministry had postponed its plan to lease five of the unarmed drones, a deal valued by security sources at around 1 billion euros, amid concerns over their future use raised by the centre-left Social Democrats (SPD) in the final months of the last coalition government.

Chancellor Angela Merkel’s conservatives and SPD agreed in their new coalition accord signed in February to lease the drones built by Israel Aerospace Industries [ISRAI.UL], while work continues on a separate program to develop a new European-built drone.

Von der Leyen said the required notification would be sent to parliament soon, but gave no details.

Defense ministry officials say lawmakers will be asked to review two separate, nearly completely negotiated contracts - one with Airbus, which will manage the drone program, and one with the Israeli government to cover training, infrastructure and logistics for the unmanned planes.

The SPD, in a surprise move, had blocked the long-planned lease of the drones last summer, citing concerns about a possible future arming of the aircraft. But SPD officials later agreed to proceed with leasing the unarmed aircraft and insisting on a full debate about the ethical, constitutional and legal ramifications of arming the drones in the future.

In a reply to a query by Left party member Andrej Hunko, dated March 5, a ministry official said the government planned to seek options for two additional Heron-TP aircraft.

Germany also plans to move ahead to negotiate the acquisition of three unmanned, higher-altitude MQ-4C Triton drones built by Northrop Grumman Corp after the U.S. State Department approved the sale on April 4.

The ministry hopes to receive a bid from Northrop for three of the drones in the third quarter, and wants to start using them by the mid-2020s, a ministry spokeswoman said.

(This version of the story adds dropped word in lead)