Berlin's decision to halt defence exports to Saudi Arabia following the killing of dissident journalist Jamal Khashoggi could hit orders for up to 20 patrol boats and cost hundreds of jobs.

Shipbuilders Luerssen, which operate out of a shipyard in the Baltic coastal town of Wolgast in the north of Germany, have already delivered 15 patrol boats out of an order for 30 to Saudi Arabia, dpa has learned.

The 16th and 17th boats, the export of which the government approved in March, are waiting in the dock and were originally scheduled for delivery to the Gulf kingdom in November.

Eight new ships are already under construction in the shipyard, which employs 300 people.

Berlin halted all permits for defence exports to Saudi Arabia following the brutal killing of Khashoggi in the Saudi consulate in the Turkish city of Istanbul at the beginning of October.

The government is considering whether the ban should also apply to exports that have already been approved, such as the Luerssen patrol boats, which are the biggest publicly known Saudi defence contract in Germany.

Each boat is estimated to be worth 20 million euros (22.9 million dollars).

If Berlin decides the ban should apply to already approved exports, it would deal a heavy blow to the local economy, where the shipyard is by far the largest industrial employer.

The current contracts are due to be fulfilled in 2020, after which there may be follow-up orders.

"The situation threatens [our] existence," Wolgast's independent Mayor Stefan Weigler said.