REPUBLIKA.CO.ID, JAKARTA -- Some 14 countries have issued a travel advisory urging their citizens traveling to Indonesia to remain vigilant and take care at all times. The warning was given following a series of terror attacks in the nation's second-largest city Surabaya.

"As of May 16, at 2:55 p.m. local time, as many as 14 countries have issued a travel advisory in connection with the terror attacks in Surabaya and Sidoarjo, Head of the Public Communication Bureau of the Ministry of Tourism Guntur Sakti stated here on Wednesday.

Countries issuing the travel advisory were the Great Britain, the United States, Australia, Hong Kong, New Zealand, Singapore, Malaysia, Poland, Ireland, Canada, France, the Philippines, Switzerland, and Brazil.

"The Tourism ministry has lauded and viewed the matter, as the countries' obligation to protecting their citizens overseas and not as a ban on visits," Sakti noted, adding that Indonesia will also follow suit for the sake of the citizens' protection.

Multiple attacks carried out by a family of six, including children, on three churches in Surabaya on Sunday (May 13) left at least 18 people dead.

Several hours thereon in the late hours of the evening that day, a bomb exploded in the Wonocolo apartment complex in Sidoarjo claiming the lives of three people.

On Monday morning, four people were killed during a bomb attack at the entrance gate of the Surabaya Police Resort Office.

The series of attacks were viewed as the worst since suicide bombers killed 20 people in Bali in 2005. At least 57 civilians, including police officers, were wounded in those attacks, the local police had reported.