Kiev said on Friday it was "cautiously optimistic" over talks with Iran to agree compensation for a Ukrainian passenger plane that was shot down near Tehran in January. Ukraine International Airlines Flight 752 was hit by two missiles and crashed shortly after taking off from the Iranian capital's main airport on January 8 amid heightened US-Iran tensions. Iran's civil aviation authority said the misalignment of an air defence unit's radar system was the key "human error" that led to the accidental downing of the plane, killing all 176 people on board. Ukraine's Foreign Minister Dmytro Kuleba said Friday he was "cautiously optimistic" over talks which lasted 11 hours and ended late Thursday. "In general, they were constructive," Kuleba said during an online briefing with journalists. He said that the two sides had agreed that Iran should carry out a "transparent and unbiased" investigation into what happened. It was too early to talk about specific sums of money Iran might pay in compensation, he said. "Of course if the negotiations with Iran are unsuccessful then we will go to international courts," Kuleba said. "But this is plan B. And plan A is negotiations," he said. Kuleba said earlier this week that negotiators would aim to maximise Ukraine's compensation over the incident in the hopes of easing "the pain and grief" felt by relatives of the victims. osh/jbr/pma