Gatland calls up more Welshmen for Lions
"We have said all along that we need to give ourselves the best chance of winning the Test series and that could potentially involve calling up players," Gatland said.
"Bringing in these players from an identical time zone, who can hit the ground running and step straight in rather than having to adjust following long-haul travel will help us manage players before the first Test, give us quality training numbers to prepare properly as well as offering us options for selection for the Chiefs match."
The Welsh quartet will attend the game against the Maori All Blacks in Rotorua on Saturday.
"These are players currently on international duty who we are looking forward to welcoming into the tour party as we did with several players in 2013," Gatland added.
"I spoke to all the Home Union coaches prior to departure and explained our thinking and they were all supportive."
There will be a further announcement regarding call-ups following the conclusion of other Home Union Tests this weekend.