(Reuters) - A World Health Organization vehicle carrying swabs from patients to be tested for coronavirus came under gunfire in Myanmar’s western Rakhine state and the driver was killed, the United Nations said on Tuesday.

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It did not say who carried out the attack in a region where fighting between the army and Arakan Army insurgents has intensified despite global calls for a ceasefire over the pandemic that has killed five and caused 119 infections in Myanmar.

The driver, Pyae Sone Win Maung, died in the state’s Minbya township on Monday, the United Nations office in Myanmar said in a Facebook post.

“The WHO colleague was driving a marked UN vehicle from Sittwe to Yangon, transporting COVID19 surveillance samples in support of the Ministry of Health and Sports,” it added.

Both Myanmar’s army and the Arakan Army denied responsibility for the attack and accused each other.

U.N. Secretary-General Antonio Guterres strongly condemned the attack, calling for a full and transparent investigation and for the perpetrators to be brought to justice, U.N. spokesman Stephane Dujarric said.

Government troops and insurgents from the Arakan Army, which wants greater autonomy for Myanmar’s western region, have been locked in fierce fighting for more than a year, but clashes have intensified recently.

“Why would the military shoot them?” said Major General Tun Tun Nyi, a military spokesman, when Reuters asked about the incident. “They are working for us, for our country. We have the responsibility for that... Everyone who has a brain knows that. If you are a Myanmar citizen, you shouldn’t ask that.”

Another healthcare worker injured in the attack is being treated in hospital.

The driver’s father, Htay Win Maung, said his son, aged 28, had worked for the WHO in Sittwe for three years.

“My heart is broken for him,” he told Reuters by telephone. “I am trying to calm myself thinking he died in serving his duty at the frontline. He went there in the midst of fighting when many people didn’t dare to go.”

Britain, the United States and other countries have called for an end to fighting in Rakhine, not least to help protect vulnerable communities from the pandemic.

The Arakan Army, along with two ethnic armed groups, declared a month-long ceasefire for April, citing the pandemic. The army rejected the plea, with a spokesman saying a previous truce declared by the government went unheeded by insurgents.