BRUSSELS (Reuters) - Europe s first ever rules on drones, which were tentatively agreed three weeks ago, risk being scuppered as EU governments hesitate over endorsing the deal because of their opposition to a drone registration requirement, among other issues. European Union lawmakers and member states finally struck a tentative deal on a long-awaited reform of the European Aviation Safety Agency (EASA) on Nov. 30, which also includes rules requiring owners of drones to register their devices if  dangerous . Such deals then need to be definitively endorsed by member states in the Council of the EU and lawmakers in the European Parliament before becoming law, something which is usually a formality. Member states were supposed to endorse the EASA reform on Wednesday, but the vote was put off when several countries, including France and Germany, expressed major concerns about elements of the deal, such as the registration requirement for drones with a kinetic energy of more than 80 joules based on their mass and maximum speed. A spokeswoman for Estonia, which holds the rotating EU presidency, said member states had until Friday to analyze the final text and say whether they could endorse it. If the EASA reform is not endorsed it risks derailing the project for months to come as negotiations between the parliament and member states will have to start almost from scratch, over two years after the initial proposal was made. The risk of the deal falling apart has unleashed a wave of lobbying from both the aerospace industry and pilots.  The emerging market of civil drones, including small as well as larger certified category of drones, has many potentials for the EU aeronautical industry. It is therefore crucial that EASA has received the mandate to put in place the safety regulatory framework for the deployment of this new technology,  the Aerospace and Defence Industries Association of Europe said in a statement ahead of Wednesday s meeting. Members include plane manufacturer Airbus, Safran, BAE Systems and Rolls-Royce. Member states had opposed a registration requirement for drones throughout the negotiations, and the European Parliament had initially pushed for a registration threshold of 250 grams. Many countries fear the 80 joules threshold is too complicated and are not happy with the compromise.  I don t think there is one happy member state around the table,  said one person involved in the discussions. The German pilots union wrote to the German transport minister on Tuesday urging him to endorse the EASA deal.    Any delay through further negotiations - as some countries are apparently envisaging - would clearly not be in the interest of aviation safety,  wrote Ilja Schulz, President of the Vereinigung Cockpit union. 