Ash spewing from an erupting volcano has closed the airport serving Indonesia's second-biggest city, as millions of people were travelling across the archipelago ahead of the Muslim holiday of Eid.
The shutdown on Thursday (local time) of the international airport serving Surabaya, on the main island of Java, came days after the airport on the nearby holiday island of Bali was closed by ash from the same volcano, stranding thousands of holidaymakers.
Authorities ordered the closure of Juanda Airport near Surabaya between 1.30pm and 8.30pm due to increased activity from Mount Raung, which has been erupting violently in recent weeks, airport spokesman Liza Anindya said.
"The concern is that the ash might affect flights," she said.
The closure came during peak holiday season in Indonesia, when people in the world's most populous Muslim-majority country flood out of cities and head to their home towns and villages to spend Eid with their families.
The celebration, which comes at the end of the fasting month of Ramadan, is expected to fall on Friday in Indonesia.
Authorities raised the alert status of Mount Raung, about 180 kilometres west of Surabaya, to the second-highest level at the end of last month as the volcano began emitting clouds of hot ash and lava.
The airport on Bali, a top holiday destination that attracts millions of foreign visitors each year, was closed twice last week during peak season - with the longest shutdown lasting two days - due to the ash.
Thousands of tourists, including many New Zealanders, were left stranded at the island's Ngurah Rai airport and almost 900 flights were cancelled or delayed, according to airport officials.
Disaster agency spokesman Sutopo Purwo Nugroho said that Mount Raung was hurling thick smoke up to 2000 metres into the air on Thursday. No evacuations of nearby residents were necessary at the moment, he added.
Air traffic is regularly disrupted by volcanic eruptions in Indonesia, which is home to 130 active volcanoes.
The main concern for airlines regarding volcanic ash is not that it can affect visibility but rather that it could damage aircraft, as it turns into molten glass when sucked into engines, according to experts.