Most member states are trying to "blackmail" Hungary in Brussels to approve a 50 billion euros ($54 billion) aid package to Ukraine, Prime Minister Viktor Orban's chief of staff said on Thursday, adding that a deal was not guaranteed.

"The prime minister conducts continuous discussions at the EU summit, we continue to strive to reach an agreement taking national interests into account, but it is not certain that this will happen," Gergely Gulyas told a briefing. (Reporting by Krisztina Than and Boldizsar Gyori; Editing by Andrew Cawthorne)