BRUSSELS — The European Union's executive body proposed Monday that the bloc's 27 nations impose more travel restrictions to counter the worrying spread of new coronavirus variants but make sure to keep goods and workers moving across EU borders.

Amid concerns related to the production and delivery of COVID-19 vaccines, the European Commission urged EU nations to reinforce testing and quarantine measures for travelers as virus mutations that are more transmissible threaten to overwhelm European hospitals with new cases.

More than 400,000 EU citizens have already died from the virus since the pandemic first hit Europe last year.

"The start of the EU vaccination campaign kicked off the beginning of the end of the pandemic," EU Justice commissioner Didier Reynders said. "At the same time, new, more transmissible variants of the virus have surfaced. There is currently a very high number of new infections across many member states. And there is an urgent need to reduce the risk of travel-related infections to lessen the burden on overstretched healthcare systems."

Among the new measures, which need to be approved by EU nations before taking effect, is the addition of a new "dark red" color to the EU's weekly map of infections. 

Reynders said this new color highlights areas where the rate of new confirmed infections in the last 14 days is 500 or more per 100,000 inhabitants. He said between 10 and 20 EU countries would already see that color on all or part of their territory if it was in effect now. 

"We also think it is necessary for essential travelers arriving from dark red areas to get tested before traveling and to undergo quarantine, unless these measures would have a disproportionate impact on the exercise of their essential function," Reynders said. 

Since the discovery of the new virus variants, several EU countries have already reinforced their lockdown measures. Belgium has introduced a ban on all nonessential travels for its residents until March, while France could soon start a third lockdown if a stringent 12-hour daily curfew already in place can't slow down the spread of new infections.

"We are suggesting stricter measures for dark red areas, because we must recognize the high level of cases," Reynders said. 

Insisting that all non-essential travel is "strongly discouraged," the commission repeated the need to keep the single market functioning so workers and goods can continue to cross borders smoothly,

"Border closures will not help, common measures will," Reynders said.

The commission also proposed that travelers from outside the EU should face mandatory coronavirus testing before they depart, tests once they arrive, mandatory quarantines for up to 14 days and hand over data for contact tracing.

It suggested EU citizens and residents take a coronavirus test upon arrival and could face further restrictions if they coming in from a country where a variant has been detected.