LONDON — The International Cricket Council plans to award Test status to Afghanistan and Ireland in a vote this week, adding the countries to the elite group of 10 nations that play the five-day format that is considered the sport’s highest level of competition.

If approved, Afghanistan and Ireland will be the first new Test countries since Bangladesh’s promotion to the sport’s most exclusive club in 2000. Both could play their debut Test matches next year.

Test cricket is still widely regarded as the summit of the sport, even as its popularity has been usurped by the faster, flashier version of the game known as Twenty20. The addition of two new nations hints at a new attempt by the I.C.C., cricket’s global governing body, to expand the Test game rather than use Twenty20 alone to increase the sport’s global profile.

More broadly, the move also suggests a newfound willingness to invest in emerging nations to improve competitiveness. Ireland has lost three players to England since 2005, but Test status would markedly increase the team’s chances of retaining the country’s best cricketers.