NAIROBI, Nov. 24 -- Kenya's military has intensified security operations in neighbouring Somalia against Al-Shabaab militants who had staged a dawn attack on a bus in the country' northern border town that left 28 people dead on Saturday.

Deputy President William Ruto told a news conference on Sunday evening that Kenya Defence Forces (KDF) have killed more than 100 Al-Shabaab insurgents after the bus attack.

"Our retaliatory action left in its trail more than 100 fatalities. It also destroyed four technicals and the camp from which this crime was planned," he told journalists in Nairobi.

Ruto said said the government had launched two across the border operations against the perpetrators of the murderous executions.

He said the rapid action by KDF is a huge victory against regional terrorist networks and noted that it emboldens the government to deliver promise to secure citizens against internal and external aggression.

"Our message to them is clear: you may sneak and attack innocent civilians but for any attack on Kenya and its people, we shall pursue you wherever you go," said Ruto.

His remarks come after about 15 heavily armed gunmen believed to be part of terrorists who crossed over to Kenya recently ambushed a passenger bus in Mandera early Saturday. All the passengers asked to come down where they separated Christians from Muslims. The Christians were then sprayed with bullets as the Muslims watched in distrust.

Al-Shabaab claimed responsibility for the heinous act which comes amid crackdown on Muslim youth in the coastal city of Mombasa.

The militants said the bus attack was in response to security raids on mosques in Mombasa and other mistreatment against Muslim community in Kenya.

"Our security forces will stop at nothing in their duty to pursue terrorists and their accomplices wherever they are," the deputy president said.

Ruto singled out political leaders who have opposed to the ongoing security operations in Mombasa, and described them as "sympathisers of the terror".

"These individuals continue to whip up emotions amongst communities and offer terrorists and their sympathisers the false comfort of civil rights protection," he said.

He accused the unnamed leaders of castigating the security forces instead of supporting government's clean-up operation.

A section of Muslim political leaders have demanded the immediate reopening of the mosques that have been sealed off to pave way for dialogue. They also expressed concerns that the government has resorted to profiling mosques in the name of dealing with radicalisation of youth in the region.

"Instead of supporting the government's clean-up operation, they have chosen to castigate the security forces, they cite the constitutional guarantees for the freedom of worship and claim that the security forces have violated this right," Ruto said.

"It is clear there are some people among us who sympathise with, harbour, facilitate and defend terrorists and their activities. The arm of the government is not short," he warned.

The deputy president said earlier that security forces launched coordinated operations on four mosques, which had been taken over by radicalized gangs in Mombasa.

Ruto, however, noted government has no intention of taking over places of worship, but warned those opposing measures being undertaken by security forces in a clean-up operation.

"It is completely unacceptable that would-be holy places can be turned into battle pavilions and holding grounds for artillery meant to inflict injury, suffering and death to Kenyans," he said.

Ruto said other radicalized propaganda literature and Al- Shabaab insignia, including flags, were found stored in these houses of worship.

The East African nation continues to suffer several attacks as terrorists change tuck to beat heightened security and carry on with their heinous acts undetected.

In the recent past, there have been numerous attacks involving shootings, grenades, or other explosive devices in Kenya. Most of these attacks occurred in northeastern Kenya, mainly in Dadaab, Wajir, Garissa, and Mandera counties, as well as along the Kenyan coast.