Newcastle captain Kevin Nolan is set to rejoin former boss Sam Allardyce at West Ham, BBC Sport understands.
The 28-year-old is still in Newcastle ahead of a medical but it is expected he will soon be reunited with his former Bolton manager at Upton Park.
West Ham said in a statement: "The club hope to announce two new signings within the next 24 hours.
"Both prospective arrivals are proven Premier League players and will add greatly to the first-team squad."
Newcastle manager Alan Pardew seemed resigned to losing Nolan, telling the Shields Gazette: "I am aware that the club made Kevin a good offer to stay, but could not agree over the length of the contract offered.
"This obviously happens in football and everybody needs to move on.
"I would like to thank Kevin for his sterling efforts as a player and captain of this club, especially since I took over last season.
"He displayed admirable leadership qualities, and I wish him every success at West Ham. It's a great club and I'm sure he will thrive there," Pardew added.
On Wednesday, Magpies midfielder Joey Barton expressed his disappointment at Nolan's proposed move away from St James' Park.
Barton wrote on Twitter: "Just on my way to Ascot, feel sick. Great player, leader, captain, person, trainer and mostly a friend for life. Devastated to see him SOLD."
Barton also hinted on the social networking site that he along with team-mates Jose Enrique and Jonas Gutierrez could be set to leave the club, writing "#mejoseandjonasnext".
However, speaking later at Ascot on Wednesday Barton stated that he wanted to stay at Newcastle.
"I have got no ambitions to leave the football club, I don't want to leave," said Barton.
"I would love nothing more so than to win a trophy at Newcastle, the same way as a number of players. Whether I get the opportunity to do that is out of my hands."
Enrique has yet to respond to the club's offer of a new deal, while Barton's agent claimed earlier this week that his player would not be offered a new contract.
Barton, 28, is out of contract next summer and could leave the Magpies for nothing at the end of the next campaign.
Magpies skipper Nolan is currently recovering from surgery on an ankle injury but is expected to be fit for the start of pre-season training.
He scored 12 goals in the Premier League last season and 18 during the 2009-10 campaign as Newcastle won promotion back to the top flight.
Nolan joined Newcastle for a fee of £4m in January 2009 from Bolton, for whom he made almost 300 appearances after joining as a schoolboy.
The Magpies skipper had been in talks with the Tyneside club over a new contract, but negotiations broke down after the two parties could not agree on the length of an extension.
It is thought that the Hammers, who were relegated from the Premier League, made an initial offer of £1.5m for Nolan.
The former England Under-21 international, who was the Football League player of the year in 2010, had a close relationship with recently recruited Hammers boss Allardyce at Bolton.
Allardyce was appointed at the start of the month and made his first signing on Tuesday with the capture of defender Abdoulaye Faye on a free transfer from Stoke.