The authorities arrested a man armed with a knife who hijacked a Sudan Airways plane Friday while flying from Libya to Sudan, police said.

The hijacker appeared to be suffering from "mental disturbances" and his motives were not known, the police said in a statement.

The police identified the hijacker as Said Faloun Said, 39, a Sudanese national, and said he was traveling on a temporary travel permit from Tripoli, the Libyan capital.

During the flight, Said entered the Airbus' cockpit and threatened the crew with a knife, demanding that the plane fly to South Africa, the police statement said.

"The crew dealt with him in a quiet, wise and responsible manner," the statement said.

When the plane landed at Khartoum airport, security officials overwhelmed Said and took him into custody, the statement said, without elaboration.