ANKARA (Reuters) - Turkey must speed up its reforms of legislation such as the sweeping anti-terrorism laws under which dozens of journalists have been jailed, the head of the Council of Europe said on Tuesday.

Since coming to power in 2002, Prime Minister Tayyip Erdogan has earned praise for reforms aimed at bringing the EU candidate nation closer to European Union norms and for liberalizing an economy that has seen unprecedented prosperity.

But his government is also accused of trying to tame the media and smother opposition.

"The lawmaking process has to be sped up," Secretary General Thorbjoern Jagland told Reuters in an interview.

"They have laws, the terrorist act for instance, special courts, and they have a very wide interpretation of what incitement to violence is, which brings so many journalists to jail."

Anti-terrorism laws allow suspects to be detained for lengthy periods before being formally charged. The media watchdog Reporters Without Borders (RSF) says Turkey has jailed more reporters than China, Eritrea, Iran or Syria, with some 70 journalists currently languishing in Turkish prisons, at least 42 of them because of their work.

In the group's 2013 press freedom index, Turkey slipped six places to 154th out of 179 countries.

Erdogan's government says most of the detained media workers are being held for serious crimes, such as membership of an armed terrorist group, that have nothing to do with journalism.

"The problem is when a journalist in Turkey reports about a terrorist group then you are immediately being associated with this group ... then you are detained and accused of enhancing terrorism," Jagland said.

"This practice and laws have a clear, chilling effect. Journalists are afraid of doing their job because they are afraid of being detained." Jagland, who was speaking ahead of a conference on freedom of expression in Ankara attended by the justice minister, said Turkey still had 450 media freedom cases pending at the European Court of Human Rights, a number he called "worrying".

The court is one of the institutions of the 47-member state Council of Europe, which aims to promote cooperation between countries concerning legal standards, human rights, democracy and the rule of law. Unlike the 27-member European Union, it cannot make binding regulations.

While Turkey has been working on a package of judicial reforms, progress has been slow. Efforts to draft a new constitution have also almost come to a halt and it is unlikely to be finished by an April deadline.

Thousands of activists, lawyers, politicians, military officers and others are also in jail on terrorism charges. Most are accused of plotting against the government or supporting outlawed Kurdish militants.

More than 300 past and present officers were convicted and handed lengthy prison sentences last September for plotting to topple Erdogan's administration almost a decade ago.

But as public support for the investigations dwindles, with critics and even sympathizers saying the number of military officers charged with sedition has spiraled out of control, Erdogan has moved to distance himself.

Last month, he criticized the lengthy pre-trial detentions, suggesting they were sapping the army's morale and affecting its ability to fight a Kurdish insurgency.