Bangladesh authorities have upgraded a 200-year-old colonial-era breakfast menu in all its prisons, an official said Sunday, as part of a reform of the country's penal system.

Bazlur Rashid, deputy head of the Prison Directorate, said the nation's more than 81,000 convicts would from Sunday receive an improved breakfast, replacing the bread and molasses that has been on the menu since being introduced by British colonial rulers in the 18th century.

The new diet will contain bread, vegetables, sweets and khichdi - a spiced rice cooked with lentils - Rashid told AFP.

Previously prisoners were given just 116 grams of bread and 14.5 grams of molasses, he said.

Bangladesh's 60 prisons, built to house 35,000 inmates, are notoriously overcrowded and frequently draw criticism from rights organisations.

Inmates also often complain about the quality and quantity of food served in the jails.

Rashid said the diet change is part of a series of reforms to "help prisoners get motivated and rehabilitated".

"We are gradually trying to adapt... so the convicts can reform themselves during their stay in the facilities," he said.

Several thousand prisoners cheered the new breakfast menu in Dhaka's Keraniganj central prison Sunday, he said, adding: "Good food makes everyone happy."

The official said the government has also introduced cheap telephone calls for inmates in the prisons.

"They would be able to talk to their family via screened phone calls whenever they want," he said.