The banks in Llanfyllin and Llanfair Caereinion were shutting following HSBC's announcement last year that it was to pull out of the towns. Councillor Peter Lewis, who represents Llanfyllin on Powys County Council, said it was a "very sad day".
"People will lose that convenience as the nearest HSBC branches now are Welshpool and Oswestry. It's sure to have an effect on the town centre and the local, rural economy, which is struggling anyway," he said.
Councillor Lewis said the alternatives don't bridge the gap for customers.
He said: "Businesses and individuals are being told they can use the Post Office but that isn't the same, people are complaining because there isn't that same level of privacy for customers. These alternatives do not stretch far enough, especially online banking which many elderly people are scared and unsure of."
North Wales AM Llyr Gruffydd accused HSBC of treating its customers with contempt. Speaking following an Assembly debate Mr Gruffydd said: "These large banks are treating us with contempt, and have shown no care for our communities.
"When banks announce their branch closures they use increased online banking as a reason to justify their actions. Yet we know that 63 per cent of women over 75, for example, or that over one in five disabled adults have never been online.
"And we've heard recently of various banks with servers going down. These banks need to realise that they are not simply profit-making companies there to milk our communities, but they also provide a necessary service."