"We must take steps to ensure that such accidents are avoided in future. Measures to that end have already been taken: we are very determined," he said in a televised speech, in which he also said he would supervise the probe into the causes of the disaster.

Earlier Sunday, Kaczynski visited the scene of the accident in Chornow and declared three days of national mourning.

Kaczynski has cancelled a one-day working visit to the Czech Republic, due to begin Monday, following the accident.

The disaster occurred Saturday, when the hall was packed with around 200 people, visiting a racing pigeon show. Besides the dead, 141 were injured in the accident.