Georgetown University researcher Badar Khan Suri has been freed from a Texas detention centre after he was arrested as part of the Trump administration's crackdown on activists across college campuses.

A federal judge ordered the release of Mr Suri, who was a postdoctoral fellow at the prestigious Washington DC institution on a student visa.

An Indian national, he was arrested outside his Virginia home on 17 March by immigration agents.

His lawyers say he was targeted "for speech in support of Palestinian rights and family ties to Gaza". US authorities accuse him of "spreading Hamas propaganda" and having "connections to a known or suspected terrorist".

The Justice Department argued the government had a right to detain him until court proceedings finished.

However, US District Judge Patricia Tolliver Giles ruled on Wednesday that his detention violated his right to free speech and due process.

She refuted the government's claims he had ties to Hamas through his wife Mapheze Saleh, a US citizen whose father was a government official in Gaza.

"There was no evidence submitted to this court regarding statements that he made" in support of Hamas, the judge said, according to the BBC's US partner CBS News.

Mr Suri's father-in-law is a former adviser to Hamas leader Ismail Haniyeh, who was killed in July last year, the Washington Post and New York Times reported.

In her court statement, Ms Saleh said her father lived in the US for nearly 20 years while studying. "Afterwards, he served as political advisor to the Prime Minister of Gaza and as the deputy of foreign affairs in Gaza," she said.

Ms Saleh said he left the Gaza government in 2010 and started an institute to encourage peace and conflict resolution in Gaza in 2011.

"Hearing the judge's words brought tears to my eyes," Ms Saleh said in a press release from the American Civil Liberties Union (ACLU), which is involved in Mr Suri's defence.

"I truly wish I could give her a heartfelt hug from me and from my three children, who long every day to see their father again," she said.

"Speaking out about what's happening in Palestine is not a crime."

The Trump administration is still seeking to deport Mr Suri in separate proceedings, the ACLU said.

Several students and academics have been investigated by US immigration officials in recent weeks, accusing them of advocating for "violence and terrorism".

Among them was Columbia University graduate and permanent US resident Mahmoud Khalil, who was arrested on 8 March after being involved in pro-Palestinian protests on campus. He was accused of having ties to Hamas, which he denies.

Badar Khan Suri's release comes days after Tufts University student Rumeysa Ozturk was released on bail after a court order.

Ms Ozturk was kept in a Louisiana detention facility after officials arrested her on the street in Massachusetts in March, and accused her of "engaging in activities in support of Hamas".