NAIROBI (Reuters) - Kenya s opposition National Super Alliance said on Sunday that one of its key strategists had been arrested in Kwale, in the country s coastal region, and that his whereabouts were unknown. The Alliance said economist David Ndii had been taken away from the Diani area late on Sunday.  The family was told that he had been taken to the Diani beach police station, but when they went there they were told he was not there nor did they know where he was. No reason was given for his arrest,  Salim Lone, an adviser for Raila Odinga, the coalition s leader, said in a statement.  NASA lawyers from Nairobi and the coast are trying to locate where he is being held,  he said, referring to the coalition by its acronyms. Charles Owino, a police spokesman, said he was unaware of Ndii s arrest, as were police in Kwale.  Police have confirmed they have David Ndii at Diani Police Station. But they want to go back to his Leopard Beach Hotel in Kwale and pick the computer and laptop for the information they need,  Dennis Onyango, Odinga s spokesman, said on Twitter. President Uhuru Kenyatta defeated Odinga in August, but Odinga challenged the election and a court voided the results, citing procedural irregularities, and ordered a fresh vote. The court s decision was the first of its kind in Africa. Odinga boycotted the October repeat poll, saying the country s election commission had failed to carry out sufficient reforms. Kenyatta won with 98 percent of the vote. Last week, Odinga said he planned to have a people s assembly swear him in on Dec. 12 - the country s independence day - raising the prospect for confrontation with security forces. Lone said that Ndii had been appointed chairman of a steering committee for the steering committee organizing for Odinga s planned swearing in.  Why has @DavidNdii been arrested and where is he being held? Is he being permitted to speak to his lawyer? Is the rule of law and due process being respected?  Isaac Okero, the president of Law Society of Kenya, said on Twitter. Kenya is a regional hub for trade, diplomacy and security. The prolonged election season disrupted its economy as investors waited to see the outcome. 