INMO General Secretary Phil Ní Sheaghdha said the HSE has confirmed the move, as all sides work to cope with the coronovirus outbreak.
She said the lifting of the ban was vital, to protect frontline health workers and prevent the virus spreading in the community.
Ms Ní Sheaghdha said: "We've been looking for the embargo to be lifted since last May. In the context of the current crisis, we have again emphasised to the health service that they need to lift all barriers because we need everybody that can be at work, at work.
"This morning they have confirmed in writing to us that all barriers are now removed to ensure recruitment of nurses and midwives."
She said the coronavirus outbreak has put hospitals under major pressure and frontline health workers need full protection amid the rising number of cases.
She said: "That includes any opportunity that we can get to prevent spread in the community.
"We already have a shortage of staff and frontline staff and we have to reduce the activities in order to match what we can provide safely."
