Two dads staging a peaceful protest on Sunderland's Queen Alexandra bridge could be there for "several weeks", campaigners have warned.
The members of the Real Fathers For Justice (RFFJ) group scaled the bridge on the morning of Father's Day before unfurling a 25ft banner saying 'Happy Fatherless Day'.
The banner has been attached to the railing on the north side of the bridge, and the pair - identified only as Danny, 42, from Wearside, and John, 34, from Gateshead - are preparing for a lengthy stay there.
RFFJ said the action, which began at about 4am on Sunday, was to highlight failings in the family courts.
The group's spokesman and co-founder, Leigh Davison, said: "Our members have so much anguish because they can't see their children.
"Father's Day and Christmas are when you see particular spikes in suicide rates among men.
"It's really difficult if you can't see your kids, especially if you know they could be just round the corner.
"Danny and John plan to stay up there as long as they can. It could be anything from several days to several weeks.
"It's like a field up there, so they could stay up there indefinitely. Another of our members, Simon Anderton, protested on the top of Tyne Bridge for 11 days last year, but it's much easier here.
"They have enough food and water to last for several days, and we can also replenish them when needed.
"It's fantastic to hear drivers beeping their horns and seeing them waving, because it shows that so much of the public understands."
Northumbria Police said it has requested the men come down from the bridge, which remains open to traffic and pedestrians, and that they will continue to monitor the situation.
Danny said he hasn't seen either of his two young children for more than four years, and dedicated the protest to his eldest son, who was born on Father's Day.
On the campaign, Mr Davison added: "We just want to get the message out there, and are calling for a more collaborative approach and mediation, so parents can be educated on how to parent apart, rather than going to family court.
"In court, a lot of the time it seems to be about proving who is the worse parent, and false allegations are rife. It's done on the balance of probability.
"False allegations can deny a child one of their parents.
"It isn't about fathers or mothers' rights, really, it is about the child's rights. They have got to have a meaningful and loving relationship with both parents.
"We offer pastoral support and an outlet for people's frustration, by campaigning against the system rather than going deeper into depression.
"If anyone is affected by contact denial or is considering family court action, we offer free initial professional advice via email only. See our website realfathersforjustice.org for more details."
The protest is similar to action taken by Simon Anderton last year, when he spent 11 days on the Tyne Bridge.
He is offering his support to Danny and John.
Mr Anderton - who is set to appear in court in November after being charged over his protest - said: "We don't do protests like this because we want to - we're forced into it.
"I love that kind of people. They're fighting for their children, my children, your children, their children and their children.
"Every person who beeps their horn gives you a massive boost. It shows the public are accepting you and keeps you up there.
"I'd ask anyone going through the same situation to come and join us. We need their support."
A Northumbria Police spokesman said: "At 5:21am on Sunday, June 19, police received a report that two men had climbed up the Queen Alexandra bridge in Sunderland.
"Officers attended and made contact with the two men, who claim to be carrying out a protest on the bridge.
"We have requested they come down and will continue to monitor the situation.
"The bridge remains open for traffic and pedestrians at this time."