Football will "no doubt" return behind closed doors but it is "impossible" to know when that will be, says the body that represents Europe's top leagues.
Alberto Colombo, the deputy general secretary of European Leagues, said the suspension of the season because of the coronavirus pandemic was "a huge crisis".
"The vast majority" of the association's members, which includes the Premier League and the English Football League, are prioritising a return to action, he said.
But he admitted that "a small number" of countries, including Belgium, were now considering cancelling their campaigns.
- What should happen to the Premier League season?
- What is the state of play in Europe's major leagues?
Football is suspended indefinitely across most of Europe because of the continued spread of Covid-19.
Premier League clubs are scheduled to meet on Friday to discuss the situation, but there is unlikely to be a resumption any time soon to a top-flight season that still has nine rounds of fixtures to play.
Last week, hopes were raised when German clubs became the first in Europe to return to training, albeit with precautionary measures in place, with talk of a resumption as soon as May.
But Colombo has urged caution, adding: "The priority so far has been on focusing on creating conditions to be able to resume competition during the summer should we be able.
"You need to resume training and develop your own protocols. There's no doubt it will be behind closed doors, so the competition organisers have to develop medical protocols, training protocols, match-operation protocols.
"But, of course, it's impossible to answer the question: 'When we will be back playing?' Nobody has these answers.
"Ultimately, we all know the governments of the countries are the ones in charge for lifting the various restrictions that apply to sport."
Germany has carried out more diagnostic swab tests - to establish whether an individual is infected with coronavirus - than other major European countries.
The Italian Football Federation hopes to begin testing players for the virus at the start of May, in preparation for the season to resume.
"There is no doubt that players' health comes first, and also the health of all those involved in matches - staff of clubs, media, everyone has to be safe," said Colombo.
"Doing testing is an important component part of these health measures. But at the moment there is not a common position in every country."
Belgium's Pro-League has annoyed European football's governing body Uefa by cancelling its season over health concerns and financial issues, although ratification is still pending and a final decision has been delayed until 24 April.
"We know there are other leagues, but really a small number, that are having these considerations," said Colombo.
"The vast majority has been focusing 100% on the resumption of their competitions.
"One of the reasons for us to maintain [this] as a priority... is to safeguard the integrity of the competitions.
"And, of course, we have to avoid jeopardising the excellent work and co-operation we have developed with Uefa during the past weeks."
Colombo added that while restarting competitions would be "good", they would respect "whatever decision a league may take".
Uefa is set to hold a video conference meeting next week to decide on the next stage in its handling of the crisis.