Abductors of the German development worker, Henriech Wolfgang, have cast aspersions on the integrity of the NGO he works for and have said they would investigate the credentials of the organisation for a week before taking any decision on releasing him.

A spokesman of the Kuki Liberation Army told newspersons at a secret location in Manipur on Friday that Wolfgang would remain in captivity till such time the integrity of his NGO, Evangelicher Entwicklungs Dienst, was established.

Self-styled director of the KLA's information and publicity wing, Malson Vaiphei, claimed his outfit had not abducted Wolfgang for ransom.

He said documents found in the social worker's possession had raised suspicion about the motive of Evangelicher Entwicklungs Dienst in funding development activity in the state. "We have doubts about the motive of the foreign NGO. We suspect a political motive behind its activities. Moreover, such development schemes have not been launched in the Kuki-dominated areas. We will conduct an investigation for a week to find out the real motive of the German NGO," Vaiphei said.

He assured that the German social worker was "safe and sound" in his outfit's custody. A senior German diplomat has been camping in Imphal since Wednesday to ensure that Wolfgang is freed at the earliest. He met a team of negotiators before they left the capital to establish contact with the abductors.

Wolfgang, who had arrived in Manipur last week to acquaint himself with the activities of the German-funded NGOs in the state, was abducted on Sunday by the KLA militants while he was on his way to Maphou dam to inspect the progress work of a community project.