The Vietnam National Administration of Tourism (VNAT) has warned travel agencies and tour operators to reconsider organizing tours to the two countries in the coming time due to safety reasons in the context of political crises and terrorist attacks in those countries.

Travel agencies that are currently taking tourists to Algeria and Sri Lanka have been asked to advise tourists not to gather in crowded places and always keep themselves updated on security statuses from local governments.

Last Sunday, a string of bombings in churches and hotels across Sri Lanka killed at least 359 people and  wounded more than 500 others. The Sri Lankan government has since revised the death toll downward to 253.

A civil war had raged for decades in Sri Lanka as its Tamil-speaking citizens fought for separatism on grounds of "deep discrimination". However, the country had been peaceful for more than 10 years after the separatists were defeated by the Sri Lankan army.

Sri Lanka, a small island nation off the southern tip of India, has been a popular tourist spot for its natural beauty as well as its Buddhist relics. Seventy percent of Sri Lankans adhere to Theravada Buddhism.

In Algeria, meanwhile, a series of protests, marches and strikes have taken place in most cities after its constitutional council met to confirm the resignation of President Abdelaziz Bouteflika.

Political turmoil in the African country has resulted in a series of terrorist attacks in recent years.

Last December, a bus carrying 15 Vietnamese tourists who were traveling from Cairo to the Giza pyramids was hit by a roadside bomb placed near a wall along the Mariyutiya Street in Al-Haram District.

The bomb attack killed three Vietnamese citizens and one Egyptian tour guide and injured 12 others Vietnamese.

Vietnam is entering its peak holiday season and many holiday-goers are planning overseas trips.

According to Mastercard, the country has the second fastest growing outbound market in the Asia Pacific region after Myanmar, with a projected annual growth of 9.5 percent between 2016 and 2021.

Mastercard has forecast that 7.5 million Vietnamese travelers will travel outside the country in 2021.