Former Watford defender Joel Ekstrand is currently training with Bristol City, head coach Lee Johnson has said.
The 27-year-old, who has two senior international caps for Sweden, is unattached after leaving the Premier League club in July.
The former Udinese man initially joined the Hornets on loan in 2012, before signing on a free transfer in July 2013, making 100 appearances in total.
“We are in the market for a centre-half,” Johnson told BBC Radio Bristol.
“It’s the one area we are probably a bit light. We invited him in.
“There is no pressure from either side at the moment. We are just assessing the situation but also the options in the market.”