The Spanish authorities have arrested four more people in connection with the
11 March Madrid bombings which left 202 people dead and hundreds injured.
The Madrid attacks have prompted security meetings across Europe
However, a Moroccan man who was being held has now been freed without charge.
The total number of people being held is now 13, some of whom are due to appear in court later this week.
Four of those detained last week now face terrorism charges, and will remain in jail while investigators gather more evidence, AP reports.
The Madrid attacks and terror threats have topped the agenda at a range of meetings by security organisations and leaders. European Union foreign ministers met on Monday to discuss the fight against terrorism ahead of the EU summit later this week.
The ministers unveiled tough measures to prevent terrorist attacks, urging member states to mobilise all their resources, including military ones, to deal with the threat.
Twenty-five senior police officers from current and future EU countries are holding a conference in the Irish capital, Dublin, and senior intelligence officials from the five largest EU countries are meeting in Madrid.
Investigators in Spain have arrested 14 people since 11 March, including seven Moroccans, two Indians and a Spaniard.
Four people were charged on Monday, after being questioned for a number of hours at the High Court, the Associated Press news agency reports.
A former miner, 30-year-old Spaniard Jose Emilio Suarez Trashorras, is accused of supplying the explosives for the attacks and faces 190 counts of murder, as well as attempted murder, robbery and terrorism charges.
The judge in the case used the figure of 190, the number of bodies officially identified so far.
Moroccan Abderrahim Zbakh faced a similar range of charges, while Mohammed El Hadi Chedadi and Abdelouahid Berrak, also Moroccan nationals, are accused of collaborating with or belonging to a terrorist organisation.
A fifth man, also Moroccan, was freed after the judge ruled that there was insufficient evidence against him.
Three of those in court on Monday were arrested in the Madrid district of Lavapies, a multi-ethnic neighbourhood where suspect Jamal Zougam, arrested two days after the bombings, ran a mobile phone shop.
Mr Suarez Trashorras admits helping Moroccans still at large to obtain explosives, but says he did not know to what use they would be put.