Mexico is not ready to sign a safe-third-country agreement with the Trump administration regarding asylum seekers at their shared border, the Mexican ambassador to the United States said on Thursday.

Martha Barcena, speaking at an event in Washington, said the United States must speed up its processing of asylum claims and that migrants cannot wait in Mexico for three years waiting for U.S. action.

She also rejected the administration’s sweeping new asylum rules announced on Monday that bar almost all immigrants from applying for asylum at the U.S.-Mexico border by requiring them to first pursue safe haven in a third country through which they had travelled on the way to the United States.

Barcena said she interprets the new rules as not sending migrants to Mexico but rather to their countries of origin.

The American Civil Liberties Union has already filed a lawsuit challenging the administration’s plan, calling it the “most extreme run at an asylum ban yet.”

The U.S. in recent months has persuaded Mexico to take limited numbers of migrants, through what it has called Migrant Protection Protocols (MPP). Critics have said the policy violates U.S. law and international norms as migrants, arguing Mexico’s crime and homicide rates don’t qualify it for safe third country status.

Monday is the deadline set by U.S. President Donald Trump last month to negotiate third country status if Mexico did not do enough to stem flow of certain migrants to the United States.