Milligan admitted he would think about his international future following the Socceroos' disappointing Asian Cup quarter-final exit to the United Arab Emirates in January.

Released by Scottish club Hibernian in May, the 33-year-old wasn't a part of Arnold's squad for the friendly against South Korea in June.

He has however recently joined English League One club Southend United and Arnold says the issue of international retirement hasn't been discussed between him and the 79-cap veteran.

"It's one step at a time for Mark. We haven't had a conversation around that issue at all," Arnold said.

"He's at Southend. He felt the best thing for his career was to be in a league where they play 50 games a year, where he will continue to play all the time.

"He made that decision and we support him with it."

Milligan, who has already played in four World Cups for Australia, will be 37 by the time the next tournament begins in Qatar in November 2022.

Arnold said Milligan will be one of several players he links up with ahead of the start of Australia's World Cup qualifying campaign in September during a trip to Europe in the coming weeks.

The Socceroos coach leaves Australia next week and will visit players in Denmark, Holland and England during his travels.

He's also keeping a close eye on several Socceroos' aspirants ahead of the qualifiers including striker Adam Taggart.

The ex-Brisbane Roar forward is topping the goalscoring charts for Suwon Bluewings in South Korea's K-League and came off the bench for the Socceroos in the 1-0 loss to Korea in Busan.

"It's great to see Adam Taggart doing fantastic in South Korea," Arnold said.

"We're watching and monitoring the players on their performance but also the minutes they're playing and their fitness as well. At the moment the boys are in great shape."

The draw for the second stage of Asian World Cup qualifying will be held in Malaysia on Wednesday evening with Australia one of 40 nations in the pot.

Eight groups of five teams will be drawn with the group winners and four runners-up to progress to the final stage of qualifying.