An employee told The Grocer staff had been informed Tesco was "not meeting sales expectations" and "Tesco needs to make strong decisions as to what financially is right".
Under the redundancy programme, the training team, which looks after stores and distribution, is to be wound up having been scaled back from 14 to six staff last year.
Certain projects that would have required significant investment are also understood to have been shelved. One such project would have involved employing 1,100 staff to man a new afternoon shift in stores in order to improve availability in the evenings. Tesco is also making some support workers redundant who work from home, though it stressed new roles would be created as well as lost.
Usdaw claimed 150 jobs were in the firing line and that it was being consulted. It would seek maximum redundancy payments for those who could not be found new roles, said a spokeswoman.
However, staff facing redundancy were doubtful they would be offered alternative jobs. "There don't seem to be any vacancies to apply for," said the Tesco employee.
"Yesterday there were only eight vacancies across the head office on the system. Given the tremendous profits the company makes it is a really poor deal."
A Tesco spokesman said the job losses were part of an annual budget review and denied they had anything to do with sales. He also insisted training remained a priority.
The number of redundancies would be "in the region of 100", he said.
"We have already announced 10,000 new jobs in the year ahead because we are opening new stores and investing in areas such as Tesco Personal Finance," he said.
"But there will be some changes to a small number of jobs."