Brazilian President Dilma Rousseff said she has ordered the Federal Police to investigate the source of a rumour that sent thousands of poor Brazilians running to state bank branches seeking payment of a monthly family stipend.

A rumour that payments of the Bolsa Familia programme would be ended led crowds to line up over the weekend at branches of the Caixa Economica Federal government bank to get their money. The rumour spread by word of mouth and cellphone text messages.

Angry beneficiaries smashed glass doors and automatic teller machines in some branches in a surprising outburst that reminded Brazilians of chaotic scenes in crowded banks during financial crises two decades ago before Brazil stabilised its economy.

The programme of cash transfers to families on the condition they send their children to school and get them vaccinated has helped lift 30mn Brazilians from poverty over a decade.

Brazil’s social policy has helped maintained widespread support for Rousseff’s ruling Workers’ Party and is a key platform in her re-election plans next year. Reacting quickly, her government allowed stipends scheduled for later this month to be paid out at ATM’s over the weekend to stop the panic.

“This government money is sacred. We guarantee these payments. We will not give up the Bolsa Familia,” Rousseff vowed in a speech at a shipyard. She called the rumour “inhuman.” “We have put the Federal Police on the case to find out who started this rumour that was aimed at unsettling Brazilians who have been rising from extreme poverty for 10 years,” she said.

Caixa Economica Vice President Jose Urbano Duarte said close to 1mn families got their Bolsa Familia cash grant this weekend.