Amir Khan responded to the recent attacks on him by Floyd Mayweather Jr on Twitter, saying that the undefeated boxing champion should stop talking and sign the contract to fight him instead.

Mayweather recently posted a photo on his Twitter account showing that he would knock out Khan once they face each other.

Khan said that Mayweather is just promoting the fight and revealed that he has already signed a contract to face the reigning pound-for-pound king.

"He's just promoting the fight," Khan said in an interview with Yahoo Sports. "At the end of the day, I'm the one who's signed the contract. I've already signed my part of the contract."

The Bolton native, who is coming off a unanimous decision win over Julio Diaz in April, is considered the leading candidate to face Mayweather. Khan called out Mayweather, saying that he should sign the contract if he really wants to face him on May 3.

"Floyd hasn't signed the contract. If he wants the fight then come on and get it. I'll fight Floyd anytime. I've said it so many times, styles make fights," Khan said.

Aside from Khan, Marcos Maidana is reportedly being considered by Mayweather after the Argentine scored a huge upset win over Adrien Broner in their WBA world welterweight title showdown Dec. 14 in San Antonio.

When asked about the possibility of Mayweather choosing Maidana over him, Khan said that he wouldn't have any problem if the Grand Rapids native chooses a fighter that he has already beaten. Khan scored a unanimous decision win over Maidana on December 2010.

"If he wants to fight a slow-handed, slow-footed guy like Maidana then he's more than welcome," Khan said. "Floyd has never fought the best guys in the era. He hasn't faced the guys who are in their prime. If he wants to face someone I've beaten to look good then so be it. The ball is in his court."

If Mayweather eventually decides to go up against Maidana, Khan revealed that he would consider facing Manny Pacquiao, who is his former sparring partner when he was still under Hall of Fame trainer Freddie Roach.

"Definitely, I'll fight Manny Pacquiao," Khan said. "It's business. I know we're friends, we respect each other but I'd definitely consider the fight. I'm sure he would as well."