Twenty-two school children on their way to start a new term are among those feared to have died on a ferry missing for 12 days between remote islands in Kiribati.

Ten primary school children were among the 88 on board, as well as 13 high school students. One 14-year-old girl was among seven survivors rescued in the central Pacific on Sunday, from a wooden dinghy that had no engine, water, food or radio.

The MV Butiraoi ferry left Nonouti Island on 18 January for a two-day, 250km (155-mile) trip to Betio, the largest township of Kiribati’s capital city, South Tarawa.

It failed to arrive as scheduled on 20 January.

The Nonouti council has gone door to door compiling a list of anyone who had family on the ferry, which was carrying no emergency rescue equipment or locator beacon, and had a recent history of mechanical problems.

Using this method, the council has confirmed that a total of 88 people – 45 male and 43 female – boarded the ferry.

The Kiribati government has been strongly criticised by families awaiting news of loved ones for its alleged disregard for marine safety, and the fact it took officials six days to call on Fiji and New Zealand for help from the air, using radar equipment and specialised marine rescue teams.

Ieremia Tabai, a Nonouti MP, slammed the vessel as “unseaworthy” and said the government should have stopped it sailing.

Planes from the US and Australia have also joined in the aerial search, but nothing of significance has been spotted in the massive search area since Sunday, rescuers have said.

President Taneti Maamau gave a second public address overnight, saying a full investigation would take place.

“The government is with you, the people of Nonouti, including those who have been greatly affected by this incomparable incident and it will not run away from it but to humbly accept it and will try its very best to search for the remaining passengers,” Maamau said on Radio Kiribati.

“There are currently six vessels helping out in the search: there are five fishing vessels and including Kiribati’s patrol boat Te Anoai, who continue to search the area of ocean where passengers and debris from the vessel might be found.”

A Kiribati medical team of three doctors and four nurses reached the seven survivors on Tuesday. The survivors are now on board the Te Anoai and being transported to the main island of Tarawa for further treatment. They are reported to be in reasonable health.

Maamau said he remained hopeful that others could still be found alive.

Former president Anote Tong told the ABC that the apparent sinking had shocked his nation and people were angry at the government as they looked for someone to blame.

“This is by far the biggest disaster in terms of numbers and also in terms of the people involved,” said Tong, who has called for a thorough investigation of the incident, saying the disaster could amount to a “criminal act” if it was found to be due to gross negligence.