• Forward said to be open-minded about a move to Celtic • 28-year-old is out of contract with Cardiff this summer

Celtic have joined the list of clubs with an interest in the Cardiff City striker Jay Bothroyd. Neil Lennon, the Celtic manager, watched Bothroyd during Cardiff's 3-0 play-off semi-final defeat by Reading in Wales on Tuesday night.

Lennon is keen to boost his attacking options this summer, with the fact Bothroyd is out of contract this summer and his physical presence both appealing factors. Celtic have been long-time admirers of Reading's Shane Long, who scored twice in Cardiff, but may be priced out of a move for the Republic of Ireland international. Long has been rated at £4m by his club, a figure that would only increase were Reading to seal promotion to the Premier League.

A source close to Bothroyd confirmed Celtic's interest in the striker, and that the 28-year-old will take two or three weeks to consider his future. He is thought to be open-minded about a potential move to Scotland, given Celtic's size.

Cardiff, who refused to sell Bothroyd in January in an effort to boost their promotion chances, fear losing the forward for nothing, three years after he signed from Wolverhampton Wanderers for £300,000. The player has been coy about his future plans.

Bothroyd's former team-mate Joe Ledley has been a key performer for Lennon this season and another Cardiff player, Adam Matthews, has signed a pre-contract to move to Parkhead in the summer.

Bothroyd appeared as a substitute for England during their friendly against France last November, after which his scoring form dipped. The forward, who finished the season with 20 goals, has been linked with Everton. Sunderland and Birmingham City have also been mentioned in relation to the former Arsenal trainee. Such clubs could get in ahead of Celtic if Bothroyd decides he wants to play in the Premier League.

The player said Cardiff would be wrong to dismiss their manager, Dave Jones, after a second successive play-off failure. The Cardiff board and Jones have said they will review his position in the coming weeks.

"Cardiff would be mad to get rid of Dave Jones. He's been great, he's brought in quality," Bothroyd said. "It's not just the manager, it's a collective thing – we're involved as well. We're the boys that go out on the pitch and play the game and he can't affect that. All he can do is pick the team."