U.S. President Donald Trump's in-laws are now officially citizens of the United States. Viktor and Amalija Knavs, Melania Trump's Slovenian-born parents, took the oath of citizenship in New York on Thursday in a private ceremony.

"It went well and they are very grateful and appreciative of this wonderful day for their family," the family’s lawyer said in a statement to CNN.

The Knavs, both in their 70s had been living in the U.S. on green cards sponsored by their daughter. They have now received their citizenship through sponsorship of their adult daughter, one of the very categories of family visas that the U.S. President has railed against.

President Trump has criticised the family-based or "chain" immigration route which is used by U.S. green card holders to bring their families to the U.S. and is a path to reunite families of foreign workers. Trump however has argued instead for a merit-based system prioritising professionals over relatives.

Melania Trump became a U.S. citizen in 2006, after entering the U.S. on a coveted Einstein visa for people of "extraordinary ability" in 2001 when she was working as a model. She had sponsored her parents thereafter for their respective green cards. Under U.S. immigration law, Melania's parents would need to have had green cards for at least five years before they could apply for citizenship.

Their lawyer Michael Wildes - who attended the ceremony with them - told reporters outside they had met the five year condition but refused to give more details, according to the New York Times.

Wildes called family-based migration "a bedrock of our immigration process", and when pressed on the fact that the President has harshly criticized family-based migration and regularly refers to it as "chain migration," Wildes responded: "I can't comment on the President's politics when it comes to my clients but I have stood up against the President's immigration policies personally."

(The above story first appeared on LatestLY on Aug 10, 2018 06:03 AM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).