Some landlords in Dublin are demanding tenants pay two months’ rent as a deposit.

The news comes as the number of people who cited the cost of rent as their number one national concern, doubled in the last year.

Labour TD and former Minister for Housing Jan O Sullivan is calling for the process to be stopped immediately and says the legality of this needs to be checked.

"The Residential Tenancies Board has the power to interevene in these kinds of disputes.," she said.

"If they're looking for two months' deposit as well as the first month's rent I'm not sure if that is actually legally allowed. I think most definitely there can be ministerial intervention if that's needed to stop this."