The 28-year-old has long been linked with a move away from the Championship side.
He told lalaziosiamonoi.it: “I spoke clearly to my club and I said to them that I would leave.
“Currently there is a standing agreement between Lazio and Portsmouth. Things are going well, I know that the two clubs have met.
“I don’t know if there will be a meeting between my agent and Lazio. I know that Lazio is in daily contact with him and also with Portsmouth.
“I am really happy that Lazio want to buy me. We are talking about a good club, a good team, one of the most important in Italy.
“I think my arrival in Rome is very likely and it will happen soon.
“Currently I think the deal between Lazio and Portsmouth has a great chance to a successful conclusion: I say 80-90 per cent.”
