The Trump administration on Friday intensified its opposition to next week's U.N. meeting to adopt a landmark pact on migration, calling it a "pro-migration" document that undermines sovereignty and warning that supporters are trying to create new international law.

The U.S. Mission to the United Nations issued the blistering three-page "national statement" on the "Global Compact for Safe, Orderly, and Regular Migration" which is to be formally approved at a high-level meeting in Marrakech, Morocco, on Dec. 10-11.

The statement claims the compact is attempting to "'globalize' migration governance at the expense of state sovereignty" and "its pro-migration stance fails to recognize that well-managed legal immigration must start and end with effective national controls over borders."

The drafting process for the global compact was launched after all 193 U.N. member states, including the United States under President Barack Obama, adopted a declaration in 2016 saying no country can manage international migration on its own and agreed to work on a pact.

But the United States, under President Donald Trump, pulled out a year ago, claiming that numerous provisions in the compact were "inconsistent with U.S. immigration and refugee policies."

In July, 192 countries unanimously agreed on the 34-page compact — the first global document to tackle migration — after lengthy negotiations on the often contentious issue, with only the United States boycotting.

But in recent months, countries including Hungary, Austria, Israel, Poland, Switzerland, Australia and Slovakia have dropped their support and said they won't attend the Marrakech meeting.

Slovakia's Foreign Minister Miroslav Lajcak, the former General Assembly president who presided over the July meeting, resigned over his country's opposition to the pact but said Friday he changed his mind after support from the president, prime minister and many others.

U.N. spokesman Stephane Dujarric said Friday that 135 countries have informed the U.N. they are attending the Marrakech meeting, and "we also expect more of them to register on the first day of the conference." He also announced that U.N. Secretary-General Antonio Guterres will attend.

Louise Arbour, the U.N. envoy for international migration who will be chairing the Marrakech meeting, expressed great disappointment last week that some countries are reneging on their support for the compact, especially because it is not legally binding and after its formal adoption "there is not a single country that is obligated to do anything that it doesn't want to."

Dujarric called it "regrettable" but stressed Friday that "this is not a closed door" and the U.N. hopes countries "will come back and continue to participate in these discussions."

"This is a non-binding pact," Dujarric said. "This is about helping countries manage migration. This is about reaffirming the rights of countries to obviously control their own borders. It seems to defy logic to see how you can manage migration without having a global conversation."

But the U.S. statement on Friday expressed concern "that compact supporters, recognizing the lack of widespread support for a legally binding international migration convention, seek to use the compact and its outcomes and objectives as a long-term means of building customary international law or so-called 'soft law' in the area of migration."

It said the word "compact" has no agreed meaning in international law, "but it implies legal obligation."