Nigerian immigration officials blocked a prominent anti-police brutality activist from leaving the country and confiscated her passport, she told Reuters on Wednesday.

There was no immediate response from immigration authorities to requests for comment on the assertion by Modupe Odele, a lawyer who has helped arrange legal defence for protesters campaigning against police violence.

Odele said that when she tried to board an international flight at Murtala Muhammed Airport in Lagos on Nov. 1, immigration authorities told her that she was under military investigation and thus barred from leaving Nigeria.

When she met immigration authorities on Nov. 3, they declined to return her passport, but did not tell her why the military is investigating her or outline any charges. Odele said the military has not contacted her.

Army spokesman Sagir Musa referred questions on Odele's case, and on whether any other protesters were under investigation or barred from travel, to immigration officials.

A spokesman for the Nigerian Immigration Service (NIS) did not respond to calls or WhatsApp messages, nor did the Department of State Services, the security agency that would bar Nigerians from leaving or entering the country for security reasons.

Nigeria's Interior Ministry on Tuesday denied local news reports that said it had compiled a "no-fly list", saying that any such list was "not the responsibility of the ministry or its associated agencies."

Peaceful demonstrations against police violence turned bloody on Oct. 20, when witnesses and rights group Amnesty International said military and police opened fire on protesters, killing at least 12.

Odele provided help to protesters as part of a group of volunteer lawyers, trying to secure the release of individuals arrested for protesting against alleged abuses by a police unit known as the Special Anti-Robbery Squad.

A human rights group called the Feminist Coalition called on Nigerians to stop protesting, and it closed off new donations after raising 147,855,788.28 naira ($388,072.94), following an appeal by President Muhammadu Buhari on Oct. 22 for an end to the demonstrations.

In a statement at the time, the group said its priority was "the welfare and safety of the Nigerian youth."