SNP Westminster leader Stephen Flynn has written to Prime Minister Sir Keir Starmer to call for a four-nation summit on tackling child poverty this summer.
Mr Flynn welcomed news the UK Government has set up a ministerial taskforce to kick-start its child poverty strategy, and said it should not delay action on the issue.
He confirmed the SNP will press ahead with its amendment calling for the two-child benefit cap to be scrapped immediately, with a vote on it expected to take place next week.
In his letter, Mr Flynn said Westminster cuts and Brexit had seen the UK become “one of the poorest and most unequal countries among our European neighbours”.
He added: “That will only change with concerted action and substantial investment from the UK Government, which has been severely lacking.
“The taskforce must not be used as an excuse to delay action.
“It is important for the governments across the isles to work together on this issue, to move quickly and to learn from best practice. I am therefore calling for a four-nations summit on eradicating child poverty this summer.
“I also think it’s vital that parties across Parliament get the opportunity to feed into the taskforce.”
The SNP says a package of measures is needed to tackle child poverty, including matching the Scottish Government’s Scottish child payment by raising universal credit by £26.70 per child, per week across the UK.
Earlier this week, Scottish Secretary Ian Murray said the UK Government wants to scrap the two-child benefit cap but it cannot afford to yet.
“It is something we want to get rid of, but we cannot afford to do that and we won’t make a promise we cannot deliver.”
Responding to Mr Flynn’s comments, a UK Government spokesman said: “As the PM has made clear, no child should be in poverty and the Government is committed to developing an ambitious strategy to reduce child poverty and give children the best start in life.
“The new ministerial taskforce will explore how we can use all the available levers across Government to create an ambitious strategy, and we will continue to work closely with all of the devolved governments as we bring forward this urgent work.”
The Scotland Office also highlighted Sir Keir’s recent meetings with devolved leaders around the UK and the new Council of Nations and Regions.
It said ministers have held meetings with poverty charities and experts, describing the work as “urgent”, while the new poverty taskforce is due to hold regular meetings.