Labour claimed local authorities across Scotland had spent the year expecting clear criteria and specifications as part of a school building strategy to be issued prior to Christmas and the Holyrood recess.
However, the delay, announced by the Scottish Government on Thursday, followed months of promises to MSPs that an update would be provided by the end of 2021.
The previous major update that included confirmation of new projects was December 18 last year.
One of the successful projects included a new Liberton High School in Edinburgh, which will see a new school constructed after 12-year-old Keane Wallis-Bennett was killed by a collapsing wall in April 2014.
However, councils will now have to wait up to another 12 months for word as to whether construction programmes will go ahead.
In answer to a written question, education secretary Shirley-Anne Somerville said the Scottish Government would announce phase three of the programme “within the next 12 months” in a 83-word update.
She said: “The Learning Estate Investment Programme has made significant progress since the first projects were announced in September 2019, with projects in construction and in development representing a £1.2 billion investment in the learning estate.
“The Scottish Government intend to announce the projects that will form part of phase three of the programme within the next 12 months.
"We will write to local authorities seeking investment proposals in 2022 and in the meantime we will work with local government to agree the development programme timeline.”
The delay was criticised by Scottish Labour’s education spokesperson Michael Marra, who labelled the update “pitiful”.
He said: “This pitiful update fails to deliver an ounce of clarity on the SNP’s plans for essential upgrades to our schools.
“Many councils have project proposals ready to go, and with this delay it puts them in jeopardy.”
He added: “The school estate is vital to curriculum delivery and learning, but too many of our schools have been left to crumble.
“The past two years have shown that much of our estate is not conducive to health and well-being – not least the ongoing failures on ventilation.
“These projects are badly needed, but yet again we have our do-nothing education secretary doing nothing.”
Responding, a spokesperson for the Scottish Government said: “Schools buildings across Scotland are in their best condition since recorded figures began. According to the latest statistics 90 per cent of schools were in good or satisfactory condition in April 2021, up from 61 per cent in April 2007.
“There is much still to do. Our £2bn programme of investment in schools, delivered in partnership with local authorities, will benefit 50,000 pupils across Scotland.
“Phase three of the programme, which we announced today, will open next year [and] provide councils with an opportunity to consider learning estate priorities for their area.
"The Scottish Government and Scottish Futures Trust are in detailed discussions with local authorities to agree the Learning Estate Investment Programme’s development timeline for 2022.”