Education Secretary Michael Gove is to examine claims the Catholic Education Service (CES) broke impartiality rules on the topic of gay marriage.
It emerged this week that the CES wrote to nearly 400 state-funded Roman Catholic schools inviting them to back a petition against gay civil marriage.
Schools and teachers are forbidden to promote one-sided political arguments.
The CES has denied breaking any laws, saying Catholic views on marriage are religious, not political.
On Thursday, the Welsh government said it was to investigate similar complaints against the CES — via redwolf.newsvine.com