Mr Robertson, strongly supported by councillors, told Highland's education committee that parent demand for Gaelic education could no longer be met because of the continuing teacher shortage and lack of initial teacher training in the north.
Matthew MacIver, registrar of the General Teaching Council for Scotland, has issued a similar plea.
In an even stronger attack, Michael Foxley, one of the council's most vociferous campaigners in the West Highlands, accused senior officials of thwarting the efforts of successive administrations to improve Gaelic teaching, a charge rejected by ministers.
Mr Robertson said: "There is a crisis. There are nine vacancies here and we are holding back demand. We cannot go out and promote interest in Gaelic-medium education because we know we cannot deliver it. We are only getting one probationer out of our allocation next session and if we advertise for full-time posts we will not be able to fill them "I cannot leave you with a strong enough impression of the danger the language is in at present. It needs action immediately."
Highland has the largest Gaelic-medium provision with 215 children in pre-school, 720 pupils in 18 primaries and 320 in secondary. There are Gaelic learner classes in 11 secondaries. Three communities have been told the authority is unable to introduce a Gaelic primary unit and a recent advertisement for six Gaelic posts attracted no applicants.
Mr Robertson said the solution lay in establishing training across the Highlands, perhaps in Fort William, Ullapool, Inverness and on Skye. The earliest that could start would be August next year.
He cited the case of a mature married woman from Dingwall who had to study at Jordanhill in Glasgow. Some of her teaching practice took place outwith Highland. "She ended up being employed in Dingwall," Mr Robertson said.
The dearth of probationers has been put down to the attractions of a career in the city and difficulties in uprooting for eight months on temporary contracts.
Drew Millar, a Skye councillor, said: "If I was 22 again and qualifying as a teacher in Glasgow, I do not think I would want to go to Staffin or Lochinver as a Gaelic teacher when the world is your oyster in Sauchiehall Street."
Financial incentives to train in remote areas, such as free child care and subsidised housing, might prove attractive to classroom assistants. Mature students and as yet unqualified adults might be better options. "We have to allow this to happen as close to home as possible and allow people to start from scratch and work from home," Mr Millar said.
Dr Foxley said the position in secondary schools was "catastrophic". A state-of-the-art secondary at Strontian, which opens in August, has only one Gaelic teacher: the head, who will teach history. Her appointment leaves a vacancy elsewhere in Highland.
Ten years ago Lochaber was described as "a wasteland for Gaelic" but significant numbers of pre-school and primary pupils were in Gaelic-medium groups in areas such as Acharacle, Morar and Fort William, Dr Foxley said. "There is formidable interest where we are able to provide it. We are having intense difficulty keeping the current system going. We are writing off dozens of schools where Gaelic would be the majority interest once it was established."
Dr Foxley blamed the lack of fast-track teacher training in Gaelic in the Highlands on Executive officials who objected to it.
David Green, Highland's convener, said his daughter, who is finishing a degree in Gaelic from Sabhal Mor Ostaig, the Gaelic College in Skye, might have taken up teaching if it had been on offer.