Wales are due to play two matches in the Pacific Islands, against Tonga and Samoa in June.
"There are still some things to iron out with Tonga, mainly that there isn't a pitch at the moment," he said.
"The stadium infrastructure is not in place so we are meeting with World Rugby again," Phillips added.
The game against the Samoans is scheduled for 24 June in the country's capital city Apia with relatively few qualms about that fixture.
But WRU representatives were in Tonga in December to look at the facilities with no completed pitch in place and continued concerns about medical cover.
Tonga v Wales in Auckland?
World Rugby stated in October: "A new venue is due to be constructed there and we need to assess whether it will be completed in time for a fixture to take place as planned."
An alternative could be to play the game in Auckland, New Zealand.
"The facilities around it [the stadium] are nowhere near what you would need to host a game, although clearly Tonga are committing to get to that," Phillips said.
"It's not particularly good for anybody at this stage. The reason it's gone on is that we all desperately want to go there and play but the pitch is fundamental to that.
"The forecast is for it to be there by May, but you are getting close to the point at which it may not be.
"Our effort at the moment is to try and make it happen, but you've got to get to a point where you say is it or isn't going to happen?
"That needs to be pretty soon now.
"The contingency would be to play in Auckland. We have got an informal agreement with New Zealand, which we did last summer when we were over there, but we'd need to kick that into plan quite quickly."
Plan B for Wales A?
Meanwhile, the return of the Wales A team is set to be delayed due to the lack of opposition for the second-string national side.
It was announced in August 2014 the outfit would return by January, 2015 thanks to a six-year agreement between the WRU and the four Welsh rugby regions.
Phillips said: "We wanted to play England and Ireland ideally, but for various reasons we haven't been able to pull that off.
"The window in which we can play is the last week of January right now.
"The worst case scenario is we play one of those two next year, at the end of January 2018.
"England and Ireland have both said they are up for the game. We have just got to land on contracting one of them.
"If we can get another fixture we will and we are talking to some other people about that."
Former Wales head coach Mike Ruddock took charge of the Wales A team the last time they played, a 30-23 win over Scotland in 2002.