Ukrainian experts are sifting through the wreckage of the Ukrainian passenger plane that crashed near Iranian capital Tehran last week, killing all 176 people on board. Iran has admitted to "unintentionally" shooting down the plane shortly after take-off, blaming "human error." Representatives of the five countries whose citizens died on the plane will meet in London on Thursday to discuss possible legal action. Reports say Tehran had agreed to hand over the plane's black boxes to Kiev for investigation.