Sheffield United have signed Dutch forward Richairo Zivkovic and Greece defender Panagiotis Retsos on loan.

Zivkovic, 23, arrives on a six-month deal from Chinese club Changchun Yatai.

Retsos, 21, will also remain until end of the season after arriving at Bramall Lane from Bundesliga club Bayer Leverkusen.

The Blades, eighth in the Premier League table, have strengthened their squad with five signings during the January window.

Club record signing Sander Berge arrived on Thursday, with Jack Rodwell and Jack Robinson joining earlier in the month.

Zivkovic, who could join the Blades permanently in the summer, reached double figures for goals while in China, with manager Chris Wilder saying: "People will recognise we do sometimes go left field with our signings, but we've worked very hard on this one, because we have had to.

"We know enough about him, we've kept tabs on Richairo for a while and tracked his progress.

"He is a Dutch international at ages under the senior level. He'll be unpredictable to other teams, but we know what we're getting and he wants to make the most of the opportunity.

"We're learning all the time this season, but pace in the Premier League is key and Richairo is someone we think can kick us on."

As for Retsos, who was born in South Africa to Greek parents, Wilder added: "He is young, talented and one that we've had our eye on for quite a while.

"He wants to prove himself in the Premier League and this initial loan spells is a perfect opportunity for him to have a look at us and us to have a good look at him."

Leverkusen managing sports director Rudi Voller said Retsos had returned to fitness after a long injury.

"It's just really important for him to play and Sheffield United can offer him one of the highest levels to come back into his top form," he added.