The deal, which has the option of a third year, is subject to a medical.
The 34-year-old Argentina captain left Barca - the only club he has ever played for - as they were unable to afford a new deal under La Liga's financial fair play rules.
Mauricio Pochettino's PSG finished second to Lille in Ligue 1 last season.
"It's all been confirmed. Lionel Messi is going to be a PSG player," Balague said on BBC Radio 5 Live. "That's it, it's done. It's happened in the last few minutes.
"At the moment there are as much police as there are fans [at the stadium]. That's going to change soon. There's eight cameras here, again that's going to change. It seems like it is a two-year deal, plus one.
"His idea was to do it at Barcelona but it's going to be PSG. Then if he feels OK he will stay one more year maybe. But in any case his aim is to be at PSG and then to do well in the Qatar World Cup."
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