David Moyes admitted he would be interested in any player he believes could improve West Ham, though he stopped short of confirming reported interest in Ross Barkley.
Midfield is an area of need for West Ham given Jack Wilshere continues to be beset by injury problems and Barkley is thought to be of interest to Moyes.
Former Everton boss Moyes handed a 17-year-old Barkley his Premier League debut back in 2011 and was asked about the two linking up again at London Stadium.
"One thing I won't do is not talk about players at other clubs," Moyes said at a news conference.
"Anything which we think will improve our side I will be interested to bring in."
Barkley played 27 times in the Premier League for Chelsea last season under Maurizio Sarri but has fallen down the pecking order at Stamford Bridge since Frank Lampard's arrival.
He started Lampard's first Premier League game in charge, a 4-0 loss to Manchester United in August, but has made only five further starts in the top flight.
A foot injury suffered in October kept Barkley out for nearly two months, while the midfielder was also criticised by Lampard after two videos emerged - one of him arguing with a taxi driver in Liverpool and another of him dancing topless in a Dubai nightclub.
On the field, Barkley scored four goals in six appearances for England in Euro 2020 qualifiers.
On the prospect of signing British players, Moyes added: "It's not easy to get British players.
"[It is] maybe easier to get a Premier League player or from abroad but still trying to get the right ones in is important.
"We are working on two or three things at the moment, but we are not close to anything."
One deal West Ham have managed to get over the line is the signing of Darren Randolph, the goalkeeper returning for a second spell in London after making the switch from Middlesbrough.
Randolph may get a chance to represent his new club on Saturday, when the Hammers host Moyes' old club Everton at the London Stadium.