LAMU, Kenya, May 29 (Xinhua) -- Kenya's security officers in coastal Lamu County have started an operation to flush out al-Shabab returnees who have secretly come back and refused to surrender to authorities for rehabilitation.

Lamu County Commissioner Joseph Kanyiri said on Tuesday that relatives and other community members who are found guilty of hiding the returnees are also targeted in the new operation.

"We are glad that a considerable number of communities have cooperated with security officers, but it's unfortunate that there are some communities that have been hiding and aiding al-Shabab," Kanyiri told journalists in Lamu.

"These communities have also remained tight-lipped whenever al-Shabab returnees come back from Somalia," he added. "We told them to surrender such people to us for rehabilitation. Investigations are a critical stage and people shall be prosecuted soon enough."

The authorities insist that the normal procedure is for the community to surrender any returnees to the police for rehabilitation after which they can be incorporated back into society.

The east African nation has announced amnesty for all al-Shabab returnees who shall surrender to the police.

Despite the assurance, not many have heeded as fears rise that it could be a trick by police to capture and eliminate the returnees.

Kanyiri said the government has adequate intelligence that many of those posing as returnees are in fact spies for the militant group.

In addition to Lamu, the coastal county of Tana River and Garissa county in northeastern Kenya are also notorious for hiding al-Shabab returnees, Kanyiri said.

Some community members in those counties have been working with militants by giving them such information as movements of security officers, he said.

Kanyiri insisted that the returnees have in fact been helping militants launch terror attacks across the region.

He warned that anyone found culpable of aiding terrorism shall be treated like a terrorist and face the full force of the law.

The militants' spies are also responsible for spreading propaganda leaflets across the region with the intent to mislead, intimidate and instill fear in residents, he said.

Locals have been asked to stay put and not allow themselves be divided along religious or tribal lines.

"People wake up to propaganda leaflets strewn all over villages in which the militants claim they have no issues with Muslims and that their main target are the Christians and tribes from outside the coastal region. We must be aware of such intentions and vow to remain sober-minded and united so we can win against them," said Kanyiri.?