Moves to tempt talented teachers into England's toughest schools with a Pounds 10,000 "golden handcuff" have been branded a gimmick.
From September, 500 of England's most challenging secondaries can offer the payments to teachers, who will be contracted for three years.
Dr Phil Dixon, director of ATL Cymru, said the idea was a gimmick and it was not the answer to attracting the best teachers to challenging schools.
"It is almost a bribe," he said.
Ed Balls, England's children's minister, hopes disadvantaged pupils will benefit - part of wider plans to improve social mobility.
The Assembly government said it had no plans to follow suit this week, a decision backed by the majority of teaching unions.
Anna Brychan, director of NAHT Cymru, said sustained help was needed for challenging schools - not cash incentives.
Rex Phillips, Wales organiser of the NASUWT, said existing staff would not receive extra cash for their loyalty, causing divisions.
An Assembly spokesman said there was already provision for incentives and benefits.
Loyalty payments, page 21.