The 26-year-old England international is currently on holiday as speculation over his future continues with the north-east duo heavily tipped to fight it out for his signature.

He will return to seek assurances over his future at Old Trafford, where he still has two years remaining on his contract.

The player is keen to stay to fight for his place, but he could be available at the right price as Sir Alex Ferguson prepares for another assault on the Champions League and the club's defence of their Barclays Premier League title.

Neither Middlesbrough nor Sunderland have commented on speculation they are among the clubs trailing the £6million-rated former Leeds frontman.

However, it is understood Boro are ready to formalise their interest as manager Gareth Southgate attempts to remodel his strike-force.

Sunderland chairman Niall Quinn declined to reveal the identities of the Black Cats' targets last week after reluctantly acknowledging their pursuit of Preston's David Nugent.

However, manager Roy Keane's relationship with Smith means he would have a head start should they commit themselves to the race for his signature.

The player said last week: "If the manager tells me he wants me, I'm there for him.

"If he says he doesn't, it's time to move on."

Both Boro and Sunderland have made strikers a priority for differing reasons as they prepare for the new campaign.

The Teessiders have moved swiftly to replace Mark Viduka following his defection to Newcastle, with Turkey international Tuncay Sanli due to undergo a medical this week before completing a move to the Riverside Stadium, and Jeremie Aliadiere also due to tie up his switch from Arsenal.

However, uncertainty over the future of 24-year-old Ayegbeni Yakubu, who has scored 35 goals in his two seasons at Boro, with Portsmouth stepping up their efforts to take him back to Fratton Park means Southgate is casting his eye over further targets.

Chairman Steve Gibson has predicted "spectacular" signings this summer, and the capture of a Manchester United player would certainly represent a statement of intent.

Southgate has admitted he is unlikely to find a like-for-like replacement for Viduka, and that could lead to a change of emphasis with pace becoming a priority.

Keane too is in the market for firepower with last season's top scorer David Connolly having managed an excellent 15 goals in 33 appearances and Daryl Murphy contributing 10 in 37 as the Wearsiders surged to the Coca-Cola Championship title.

Quinn admitted Sunderland face stiff competition for Nugent's signature - West Ham have since been heavily linked with him, while Everton has long been touted as his preferred destination - but insisted there were other targets as well.