The Fifa secretary general, Jérôme Valcke, has defended the organisation's rankings that have placed England fourth in the world and Brazil 11th but has admitted the system can sometimes appear to be "not very logical".

England rose two places after their Euro 2012 campaign with only Spain, Germany and Uruguay ahead of them – and are expected to achieve a highest-ever ranking of third next month.

The beaten Euro 2012 finalists Italy, who defeated England in a quarter-final penalty shootout, are sixth while Brazil have dropped from fifth to 11th – as the 2014 World Cup hosts they do not play any competitive qualifiers so do not gain as many ranking points.

The rankings determine whether teams will be seeded in the draw for the next World Cup. "I know that these rankings are sometimes quite difficult to understand due to the level and numbers of criteria that are taken into account," Valcke told Press Association Sport.

"There are teams who are playing more friendly games than other teams and you can see a difference which is not very logical, but the ranking I would say is clearly still a good picture of the level of international football.

"Brazil are not playing official games, just friendly games as they are already qualified. There have been internal meetings and also with the football committee to discuss the ranking of the different nations. We want to be able to explain in an easier way how this ranking is based."

The Fifa rankings are based on an international side's results over the previous four years, with more points awarded from competitive matches than qualifiers, and weighted even more strongly towards matches in the final tournaments of World Cups and continental tournaments such as European Championship.

England have benefited from the fact that their failure to qualify for Euro 2008 no longer counts against them when the rankings are calculated.

The Republic of Ireland, who lost all three matches at Euro 2012, fell eight places to 26th in the latest rankings. By contrast, the Republic rose five places in the first Fifa rankings following the 2010 World Cup, despite failing to qualify for the tournament in South Africa.