A Nigerian senator has been charged over his alleged links to the Boko Haram Islamist militants who have staged numerous deadly attacks in recent months.
Ali Ndume has been questioned by secret police since Monday night.
He denied charges of intimidation and breach of trust after an alleged Boko Haram spokesman said Mr Ndume had paid him to send threatening text messages.
Boko Haram recently killed at least 63 people in a series of raids.
In August it bombed the UN headquarters in Abuja, killing 24 people.
Mr Ndume is a member of a presidential taskforce, which explored the possibility of opening talks with the Islamist militants.
He is a senator from Nigeria's ruling People's Democratic Party from Borno state, where Boko Haram first emerged.
Boko Haram means "Western education is forbidden". Parts of the group say they want Sharia, Islamic law, more widely applied across Nigeria, but correspondents say most factions are focused on local issues.
It has carried out many attacks on police and government institutions in both Borno state and more recently other parts of the country.
The secret police (SSS) said on Monday they had discovered links between Boko Haram and regional politicians after the arrest and questioning on 3 November of the group's alleged spokesman Ali Sanda Umar Konduga.
Police alleged Mr Konduga was the Boko Haram spokesman quoted in the Nigerian media using the name Usman al-Zawahiri.
"His arrest further confirms the service position that some of the Boko Haram extremists have political patronage and sponsorship," SSS spokeswoman Marilyn Ogar said.
The statement also said Mr Konduga had been behind threatening text messages sent to judges and politicians, which he said Mr Ndume had paid for.
Boko Haram launched an uprising in Borno in 2009 which was put down by the Nigerian military. Boko Haram's leader, Mohammed Yusuf, was captured by the army, handed over to the police, and later found dead.
The group has since re-emerged, carrying out a series of shootings and bombings.
There has been speculation about whether Boko Haram has links with external extremist groups, including al-Qaeda's North African branch.