The Danish coaching staff have been in touch with Riis and PNE team-mate Daniel Iversen recently.
The striker – who joined the Lilywhites last year – has scored eleven goals in 21 appearances for Preston this season.
Riis told the Lancashire Post: “I got a call from the Denmark assistant manager saying that I was close but not there just yet.
“He told me he’d really enjoyed watching me and just to keep on going.
“I don’t think he’s been over to watch the games, it’s been on television.
“It’s nice to know they are watching me and playing for Denmark is a goal I have set for myself.
“I have Under-21 caps but didn’t play a lot of games.
“Last season I was in and out of the team at Preston so it was hard to get into the Under-21s team.”
Here are the best of today’s rumours...
1. Barcelona and Borussia Dortmund tracking Blades striker
Barcelona and Borussia Dortmund are reportedly monitoring Sheffield United striker Daniel Jebbison, who is currently on loan at Burton Albion. The 18-year-old has scored three goals in 11 appearances for the Brewers. (The 72) Photo: Christian Kaspar-Bartke
2. Stoke City could green light attacker's departure
Stoke City could be ready to allow Abdallah Sima to return to his parent club Brighton & Hove Albion in the January window amid the Seagulls' injury crisis. The 20-year-old has made only two Championship appearances for the Potters this season. (The 72) Photo: Graham Chadwick
3. Sheffield United to push for Barcelona man in January
Sheffield United remain keen on Barcelona's Alex Collado and will push to sign the Spaniard in the January window. Slavisa Jokanovic was hopeful of a deal in summer but it broke down. (Football League World) Photo: Eric Alonso
4. Everton starlet wanted by Blackpool
Blackpool want to resign Everton's Ellis Sims after his successful loan spell at Bloomfield Road last season. The forward scored ten goals for the Seasiders. (Liverpool Echo) Photo: Nathan Stirk