Leagues and clubs across Europe have been warned that cancelling competitions due to the coronavirus pandemic at this stage is "premature" and "unjustified".
The Belgian top flight became the first to conclude its campaign on Thursday, with Club Brugge declared national champions.
A letter from the presidents of European governing body UEFA, the European Club Association and the European Leagues group to national associations, leagues and clubs said cancellation should be a "last resort", and said plans are being worked on for play to continue into July and August, with the Champions League and Europa League to be completed afterwards.
"With no unity and no solidarity, nobody will be able to get out of the crisis as we are all interdependent," the letter warns.
A working group is looking at the fixture calendar, and the letter stated it will advise as soon as possible – and ideally by the middle of May – about which plan for resumption to follow.
"Their work is now focusing on scenarios encompassing the months of July and August, including the possibility that the UEFA competitions restart after the completion of domestic leagues," the letter continued.
"A joint management of calendars is strictly required as the conclusion of the current season must be co-ordinated with the start of the new one, which may be partly impacted because of the overstretch.
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"Stopping competitions should really be the last resort after acknowledging that no calendar alternative would allow to conclude the season."
The recipients of the letter were also warned that cutting leagues short unilaterally would cast doubt on clubs' eligibility to enter European competition next season.
"Since participation in UEFA club competitions is determined by the sporting result achieved at the end of a full domestic competition, a premature termination would cast doubts about the fulfilment of such condition," the letter added.
"UEFA reserves the right to assess the entitlement of clubs to be admitted to the 2020-21 UEFA club competitions, in accordance with the relevant applicable competition regulations."
A second working group has been set up by UEFA to look at the economic and regulatory impact of the Covid-19 outbreak, including the issue of standard player contracts which expire on June 30.
On Wednesday UEFA postponed international matches due to be played in June, including the Euro 2020 play-off ties, clearing the way for domestic league action should circumstances allow football to return by then.
