Plans for a new national reading test for six-year-olds will feature monsters and rely on children being able to read nonsense words such as zort and koob.
The test is designed to pick out children who have problems with understanding phonics, according to proposals unveiled this week.
But it has already come under fire from literacy experts, who have said that children who cannot read may still do well in the test, while those who can read may be stumped.
This year, 15 per cent of pupils did not reach the expected Level 2 in reading at the end of Year 2, prompting the introduction of what ministers claim will be a 10-minute screening check administered at the end of Year 1.
It will include real and nonsense words to help ensure pupils have not merely memorised words. In order to provide a context for these words, it is suggested that teachers show a picture of an imaginary creature and explain that the non-word is its name.
Unions say that many teachers already use this test - the last government included a nonsense-word assessment in its Letters and Sounds programme, which was distributed free to all primary schools.
NUT general secretary Christine Blower said: "It seems to have escaped the Government's attention that teachers are assessing pupils all the time, that's what they do, and there is already plenty of information from which teachers can work.
"Teachers and parents are more interested in the support available to children who are finding it difficult to learn how to read - the costs of introducing yet another test would be far better spent on investment in helping this group of children."
Martin Johnson, deputy general secretary of the Association of Teachers and Lecturers, said: "Phonics screening would be bad news for children, bad news for schools, and bad news for the country, which needs a modern and grown-up debate on improving standards of literacy."
The Government said that teachers are expected to assess children's wider reading skills, but the phonics test will confirm whether pupils have learned this important skill to an appropriate standard.
Making the test mandatory will ensure that Ofsted and the Government have the information to monitor standards nationally, it added. The results will be given to parents but won't be published.
However, the UK Literacy Association (UKLA) has warned that such tests are not useful for showing children's progress in reading.
Henrietta Dombey, professor emeritus at the University of Brighton and a member of the UKLA executive, said: "It is a mistake to think that the ability to accurately read a whole lot of non-words is an essential basis for learning and reading.
"Recognising words in isolation is not the same thing as reading. There is a lot of evidence to show that children as well as adults find it easier to recognise words in a meaningful context. Effective young readers expect words they read to make sense and if a text fails to make sense that gives them a prompt to go back and look again - you don't get that with non-words."
The test is due to be piloted next June and then rolled out, subject to evidence, in June 2012.
Upon my word
Is this a pronk?
Thousands of children already recognise made-up names and monsters through the popular Flaminals books, written by actor and comedian Ricky Gervais (left).
The books feature characters with names such as the Honk, Grundit, Puddloflaj and Mernimbler. Responding to the Government's phonics test, Mr Gervais told The TES: "New words are introduced to our vocabulary every year to reflect trends and innovations in popular culture. No one wants to be left behind and out of touch.
"I think it's flambulatory not to condone this test. Only crunts would oppose it. If it turns a generation of kids into absolute swog monglets, then so be it."