London - Calls to Britain's national domestic abuse hotline have jumped 25% since the U.K.'s coronavirus lockdown began a little more than two weeks ago, according to Refuge, the charity that runs it. Activists had warned that the stay-at-home orders could lead to an increase in domestic violence.

"Ordinarily, the window for women to seek help is extremely limited," Sandra Horley, chief executive of Refuge, said in a statement Monday. "During periods of isolation with their perpetrators, this window narrows further. It is critical that women have alternative, digital ways of accessing help."

Refuge said visits to its website had increased by 150% over the same period, stressing that while the COVID-19 pandemic may be exacerbating the problem, it is not causing it.

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"Domestic abuse is a crime and is ultimately rooted in power and control. Violence is a choice a man makes. He alone is responsible for it," Horley said.

"It's obviously been getting worse since the lockdown."

Tara, whose name has been changed to protect her identity, told BBC News that she fled her abuser a few days ago after things got much worse under the lockdown.

"As soon as he gets up, he tries to cause an argument out of nothing, and if I fire back he'll just hit me," she said.

Tara's abuser deleted her social media accounts, isolating her from her friends and family.

"It's been bad… I didn't care if I didn't wake up like from the night before," Tara said. "I just knew what was going to happen the next day. I just wanted the days to go past."

"Horrifying global surge in domestic violence"

Overnight Monday, U.N. Secretary General António Guterres released a statement calling for plans to tackle domestic violence to be included in all national efforts to contain COVID-19 outbreaks.

"We know lockdowns and quarantines are essential to suppressing COVID-19, but they can trap women with abusive partners," Guterres said in a video message on Twitter.

In France, women are being urged to go into pharmacies and use the code world, "Mask 19" if they need help, so their abusers will think they are trying to buy face masks rather than call authorities.

In his statement, Guterres said emergency warning systems like the Mask 19 initiative should be set up in grocery stores and pharmacies across the world, and that domestic abuse shelters should be declared essential services.

"Together we can and must prevent violence everywhere, from war zones to people's homes, as we work to beat COVID-19," he said.

If you are a survivor or victim in the U.S. and it is an emergency, dial 911. Other resources include: The National Domestic Violence Hotline at 1-800-799-SAFE, or text LOVEIS to 22522. If it is an emergency in the U.K., call the police at 999, or for additional resources in Britain, you can dial the National Domestic Abuse hotline at 0808 2000 247.