Kenyan authorities have enhanced security in and around the country's main airports to help prevent terror attacks at the country's key entry points across the country.

Kenya Airports Authority (KAA) which manages all airports across the East African nation said Wednesday it has intensified security checks at the airports and have a advised passengers to arrive an hour before normal reporting times.

"Due to security enhancements at all airports, passengers are advised to arrive for their flights at least one hour before the normal reporting time to cater for vehicle security checks during entry to the airports," KAA said in a newspaper advertisement on Wednesday.

The heightened security follows a blast which occurred at the Jomo Kenyatta International Airport (JKIA) last week causing damage at the departure section.

The police chief said there was no casualty despite the despite the heavy presence of security forces and bomb experts who had been called in immediately after the "explosion".

The security forces said last Saturday they have arrested four suspects in connection with the blast last week at the main airport.

Police spokesperson Gatiria Mboroki told journalists in Nairobi that further investigations are ongoing so as to ensure the culprits are brought to book.

"We are also asking Kenyans to remain vigilant as several attempted incidence of terrorist attacks have been noted in the past week," Mboroki said.

On Wednesday, Kenya Airways advised its customers departing from JKIA in Nairobi to plan to be at the airport at least an hour before normal check-in time as police heighten security checks.

"Following enhanced security measures implemented by the KAA, Kenya Airways wishes to advice all guests departing from JKIA in Nairobi to plan to be at the airport at least an hour before normal check-in time," the airline said in the statement.

"This is to allow for sufficient time to go through the enhanced security checks and be on time for scheduled flights," the statement said.

The enhanced alert follow indications of a terror attack in the wake of the start of the trial of four men accused of being behind the Westgate attack last September, in which more than 68 people died and the airstrike by Kenyan troops in Somalia early this month.

The enhanced security also comes amid reports that some of the Kenyan youths who had crossed to the Horn of Africa nation to join the militants are now back in the Coastal region after being discouraged by the constant military attacks on the militants' strongholds and fallouts.

The police said more border patrol will be intensified along the Kenya-Somalia border in Kiunga and Dadaab refugee camps to prevent the Al-Qaida-linked insurgents who are fleeing Kismayo to from entering into the country.