The MCC Cricket committee and MCC World Cricket committee both believe Test cricket should continue to be played over five days.
It could be the final nail on the "four-day" head.
The MCC has given its backing to the continuation of five-day Test matches, amid debate over whether cricket's longest format could be shortened.
Tim May, a member of the MCC World Cricket Committee, also has a seat on the ICC's Cricket Committee, while the MCC, the owner of Lord's, is also represented.
The Marylebone Cricket Club's world cricket committee - which includes Ricky Ponting and Shane Warne - advised against a four-day Tests as recently as 2017.
"The MCC Cricket committee and MCC World Cricket committee have actually recently discussed the issue and though they are able to see some advantages that four-day Test cricket could deliver, both committees think that Test cricket should continue being played over five times".
Four-day Test matches would be likely to follow the playing conditions used for the handful of recent four-day Tests, with 98 overs scheduled for each day rather than 90.
India captain Virat Kohli has been among many cricketers who have objected to the ICC's proposed four-day Test format.
A third could also be played next summer when Australia host Afghanistan.
The English and South African cricket boards favour the concept, while the Federation of International Cricketers' Associations remains sceptical of any such move. Kevin Roberts, chief executive, said last month that the four-day tests were part of the feedback they received from a survey of 8,000 Australian fans.