Giles Clarke, the ECB chairman, faces the greatest test of his negotiating skills to persuade wavering boards that Zimbabwe should not participate in the ICC World Twenty20 tournament in England next year. Despite prompting from South Africa, Zimbabwe Cricket was still reluctant last night to step down voluntarily on the back of poor results.

A day of heated talks by the ICC board ended without resolution and, according to a source, the outcome “hangs on a knife edge”. Options appear to be a competition in England without Zimbabwe, who have been denied entry by the British Government, or a tournament elsewhere boycotted by England and possibly other countries.

The prospect of a big split in the sport, long threatened, is sure to refocus minds after days of posturing. Clarke, who is under instruction from the Government to take a robust line, looked drained when he emerged from the eight hours of meetings. The Zimbabwe Cricket delegation seemed bullish in chatting over strategy in the lobby of the Westin Hotel.

The ECB has all but given up on its preference for Zimbabwe to be stripped of full-member status, which would mean a big drop in funding. In the uncertainty, any realistic option to remove Zimbabwe from the event next June would be taken as an acceptable compromise. India, Bangladesh and Zimbabwe seem fixed against this move, while Australia, New Zealand, South Africa and West Indies are Clarke's most likely allies, with Sri Lanka and Pakistan thought to be uncommitted.

The ECB will confirm today that Sri Lanka will replace Zimbabwe next May for Test matches at Lord's and the Riverside and one-day internationals at Bristol, Edgbaston and Headingley. But there is no guarantee that Sri Lanka will side with Clarke because India have bailed them out of financial trouble by touring next month.

South Africa, who put the Zimbabwe issue on the agenda, have changed emphasis from a political argument to a pure cricketing case. Zimbabwe have won only two of their past 32 one-day internationals, but they did beat Australia in the World Twenty20 in South Africa last year.

While the British Government has yet to state explicitly that the Zimbabwe squad will not be granted visas for the competition, Andy Burnham, the Secretary of State for Culture, Media and Sport, has hinted that bans for the one-day series, which have now been shelved, would be extended. Reports of tension within the South Africa party suggest that Clarke may have to take the lead in presenting a final case this morning. He is in a position to win support in the area where the ICC is usually most receptive: money.

Tickets for the tournament went on sale on Monday and by yesterday evening the only seats available for the latter stages were in the family stand for a match at Trent Bridge in the Super Eights, which, if things go as seeded, will be a double-header involving New Zealand against Bangladesh and England versus South Africa.

This ought not to enter a pure cricketing argument, but as students of ICC politics will know, matters are rarely pure and certainly never simple where the governing body is concerned. At least it managed to agree early yesterday that the constitution allows discussion of Zimbabwe's status, albeit under “any other business”.

The meeting did decide, though, to change the result of the Brit Oval Test against Pakistan in 2006 from an England win to a draw. Pakistan forfeited the match when they refused to return to the field after being accused of ball-tampering by Darrell Hair, the umpire. England will now be ruled 2-0 rather than 3-0 series winners.

The Pakistan Cricket Board argued that Hair, later dropped from the ICC umpiring panel, went beyond his authority and that Inzamam-ul-Haq, the captain, was subsequently cleared of the charge. But the verdict flies in the face of the Laws of the game and sets a dangerous precedent for disgruntled teams who may feel that they are behind in a match.