Rabi Lamichhane had become deputy prime minister and the powerful home minster after his newly formed party joined the coalition government last month.

He was once a United States citizen but gave it up after returning to Nepal.

The court ruled that after he took up US citizenship he was no longer a Nepali national, and that after abandoning his US citizenship he did not reapply for Nepali nationality.

Therefore, it said, he improperly contested the election because of his invalid citizenship.

Nepal does not allow dual citizenship.

Lamichhane walked out of the government ministry and told reporters he welcomed the court decision.

He said he was now without any citizenship and was unable to make any comments.

There was no immediate comment from the government or the prime minister's office.

Lamichhane, a former television host, formed the National Independent Party with people who had no connections to political groups.

The party won 20 seats in the November 20 election for the House of Representatives, the lower house of parliament.

Australian Associated Press