Poland is in mourning over the deaths of President Lech Kaczynski and much of its defence establishment in a plane crash in western Russia yesterday. All 97 people on board the jet, died when it crashed in fog near Smolensk air base. They were due to attend a memorial for victims of a wartime massacre. Russian officials say pilots ignored warnings they were flying too low. A week of mourning has been called in Poland where a two-minute silence will be held at noon today. (3.30 pm IST) Russia has also declared tomorrow a day of mourning for the victims, whose remains have been flown to morgues in Moscow. Officials said relatives of the dead have begun arriving in the Russian capital. Russian Prime Minister Vladimir Putin has said he will personally oversee the investigation into the crash.