The aviation hub, a key gateway for people arriving in Asia, joins other countries in the region that have recently dropped travel curbs as they shift to living with Covid-19.

Previously, only travellers from a handful of places could enter Singapore without quarantining but from Friday all vaccinated arrivals just need a negative Covid test.

The city-state's Changi Airport buzzed with activity as passengers streamed out of the arrival area, while hundreds were lining up in the departure zone to make trips outside Singapore.

"It's wonderful," Aldo Pizzini, a 63-year-old Italian businessman who had flown in from Milan, told AFP.

"I took the first opportunity to fly today, (now) that much of the restrictions are lifted... We are coming back to normality."

Diana Mathias, who is from French Guiana and lives in Abu Dhabi, was visiting Singapore for a holiday with her mother.

"I feel really happy because it's a long time since I flew," she said.

The 38-year-old said she was a "bit stressed" at the prospect of doing a lot of paperwork to travel again but in the end found the process "really easy".

Borders also reopened fully in neighbouring Malaysia on Friday, and thousands of cars and motorcycles flooded across a one-kilometre (0.6 mile) causeway that separates it from Singapore.

The causeway, one of the world's busiest land borders, had already partially reopened last year although some curbs were still in place.

The main airport serving Kuala Lumpur was busy as foreign tourists arrived.

Previously tourists were barred from entering Malaysia, a popular destination due to its white-sand beaches and lush rainforests, but vaccinated travellers can now do so with only a negative Covid test.

Bo Lingam -- group CEO of leading regional carrier AirAsia, which is based in Malaysia -- predicted a "surge" in people flying.

The reopening of borders is "a joy for me and our AirAsia staff who had to face a lot of hardship during the pandemic", he told AFP.

"From today, it is all about flying the blue skies and an end to our planes sitting on the tarmac."