VIENNA (REUTERS) - Vienna has dislodged Melbourne for the first time at the top of the Economist Intelligence Unit's (EIU) Global Liveability Index, strengthening the Austrian capital's claim to being the world's most pleasant city to live in.

The two metropolises have been neck and neck in the annual survey of 140 urban centres for years, with Melbourne clinching the title for the past seven editions.

This year, a downgraded threat of militant attacks in western Europe as well as the city's low crime rate helped nudge Vienna into first place. It is the first time a European metropolis has topped the annual chart. Vienna regularly tops a larger ranking of cities by quality of life compiled by consulting firm Mercer.

In Asia, Osaka and Tokyo moved up the ranks to join EIU's top 10 most liveable cities, coming in third and seventh place respectively.

Singapore is the 11th most liveable city in Asia, but fell two places to 37th spot overall, while Hong Kong climbed from 45th to 35th spot overall. Singapore had overtaken Hong Kong to take the 35th spot in 2017.

Although Hong Kong was overtaken by Singapore in the rankings for the first time in 2017, the city surpassed Singapore this year, albeit with only a marginal difference in score of 0.1 per cent overall, said The Economist in a press released issued on Tuesday (Aug 14).

"In its own turn, Singapore's score also registered an improvement in the public healthcare category, boasting the highest possible score," the press release added, without elaborating.

Hong Kong's South China Morning Post reported that the annual EIU survey attributed the city's better score this year to lower levels of social unrest four years after the pro-democracy Occupy Central movement rocked the city.

As for the liveability scores of Chinese cities, the EIU said there have been no major changes over the past year.

Shenzhen, it said in the press release, registered a modest improvement of 0.7 per cent after it electrified its entire fleet of public transit buses.

"This measure is one of the first successes in a nationwide effort to transition to electric vehicles, whose larger impact on liveability in Chinese cities, and especially in the Greater Bay area, remains to be seen," said the press release.

At the other end of the table, Damascus retained last place, followed by the Bangladeshi capital Dhaka, and Lagos in Nigeria.

Increasing pollution is another factor affecting liveability, especially in South Asia.

The survey does not include several of the world's most dangerous capitals, such as Baghdad and Kabul.

"While in the past couple of years, cities in Europe were affected by the spreading perceived threat of terrorism in the region, which caused heightened security measures, the past year has seen a return to normalcy," the EIU said in a statement about the report published on Tuesday.

"A long-running contender to the title, Vienna has succeeded in displacing Melbourne from the top spot due to increases in the Austrian capital's stability category ratings," it said, referring to one of the index's five headline components.

Vienna and Melbourne scored maximum points in the healthcare, education and infrastructure categories. But while Melbourne extended its lead in the culture and environment component, that was outweighed by Vienna's improved stability ranking.

Osaka, Calgary and Sydney completed the top five in the survey, which the EIU says tends to favour medium-sized cities in wealthy countries, often with relatively low population densities.

Much larger and more crowded cities tend to have higher crime rates and more strained infrastructure, it said.

London, for instance, ranks 48th.

Vienna, once the capital of a large empire rather than today's small Alpine republic, has yet to match its pre-World War I population of 2.1 million. Its many green spaces include lakes with popular beaches and vineyards with sweeping views of the capital. Public transport is cheap and efficient.

In addition to the generally improved security outlook for western Europe, Vienna benefited from its low crime rate, the survey's editor Roxana Slavcheva said.

"One of the sub-categories that Vienna does really well in is the prevalence of petty crime... It's proven to be one of the safest cities in Europe," she said.