Hungarian police say they have arrested a fifth man over the deaths of 71 people, thought to be migrants, found in an abandoned lorry in Austria
The man is the fourth Bulgarian to be held over the find near the Hungarian border. The other man is Afghan.
Meanwhile, Germany, France and the UK have called for urgent EU talks on the escalating migration crisis in Europe.
On Sunday, France's foreign minister said the attitude of several countries towards the crisis was "scandalous".
Hungarian police said in a statement that the fifth man was arrested late on Saturday "on suspicion of committing the crime of people smuggling".
Authorities believe the men are low-level members of a human trafficking gang and hope the arrests will help them uncover the leaders of the group.
In a court hearing on Saturday, the four men arrested last week insisted they were innocent. Austria could seek to have them extradited.