* Engineering giant demands inquiry Khashoggi's killing
* Siemens CEO's decision comes amid international outcry
* Siemens has 2,000 workers in Saudi, Aramco among partners (Adds Altmaier comments, foreign ministry meeting with Saudi envoy, industry response)
BERLIN, Oct 22 (Reuters) - Siemens's chief executive said on Monday he would not attend a three-day Future Investment Initiative conference in Saudi Arabia after the country admitted that journalist Jamal Khashoggi had been killed in its consulate in Istanbul.
The German engineering giant was one of the last companies to decide against sending its top executive to the conference after Riyadh sought to cover up Khashoggi's Oct. 2 death before admitting to a "grave mistake".
"Siemens is a reliable and committed partner of the kingdom and its VISION 2030. But for now, truth needs to be found out and justice applied," Siemens CEO Joe Kaeser said in a statement posted on his LinkedIn account outlining his motivation not to travel to the conference in the Saudi capital Riyadh.
"Time will tell how things will develop. And I do hope there will be clarity, transparency, and justice sooner rather than later," he said.
Khashoggi's killing in Istanbul had been "monstrously planned", a spokesman for Turkey's ruling AK party said on Monday. An adviser to Turkey's president rejected Riyadh's assertion that Khashoggi died in a fight, suggesting this "mocked" international opinion.
Germany, Britain and France have pressed Saudi Arabia to present all the facts in the killing, and Economy Minister Peter Altmaier urged other European Union states to join Germany in halting arms sales to Saudi Arabia as long as uncertainty over Khashoggi's fate persists.
Merkel's spokesman Steffen Seibert on Monday said officials would review what to do about arms sales that had been approved but not exported. The head of the BDSV arms makers trade group told the Handelsblatt daily that German companies needed clear answers soon about equipment already being built.
Germany's foreign ministry on Monday also said it had asked the Saudi ambassador to come to a meeting at the ministry to discuss fallout from Khashoggi's killing.
Last week ABB Chief Executive Ulrich Spiesshofer said he would skip the meeting, following the lead of Airbus defence chief Dirk Hoke, Deutsche Bank CEO Christian Sewing and others..
Senior finance and trade officials from various Western governments including the United States will also shun the forthcoming conference because of Khashoggi's killing.
Kaeser said his decision to skip the event was no condemnation of the Saudi population or a value judgment on Siemens's 2,000 local employees in Saudi Arabia and partners like Saudi Aramco, SABIC, SEC and the Abunayyan group.
Kaeser said he wanted to consider the interests of all stakeholders, taking into account a business opportunity worth up to $30 billion by 2030 as well as the company's reputation, before taking a decision.
"But sometimes, situations develop in such a way that no one can win, where every option is wrong. The so-called Khashoggi crisis, the death of Jamal Khashoggi, is such a situation." (Reporting by Tassilo Hummel and Edward Taylor; Editing by Maria Sheahan and Richard Balmforth)