The 173 million pound ($A267.2 million) cash retention fees due to be paid to 73 Xstrata executives will now be paid in shares of the merged group.

The retention awards included around $A45.5 million for chief executive Mick Davis.

Xstrata said the changes came after it consulted with shareholders and advisors over the past few days in response to feedback.

In recent days Standard Life Investments head of equities David Cumming was reported as saying Davis should resign to allow the merger to proceed.

“There's just no support for the deal as it stands and the credibility of Xstrata's board and management team aren't there anymore,” he told the BBC.

His comments came just days after investor group the Association of British Insurers gave its own thumbs down to the “golden handcuff” packages, citing corporate governance concerns because the payments weren’t related to performance.

Xstrata moved to address those concerns also, with the payments now to be subject to performance criteria based on realising additional cost savings over and above the $US50 million expected in the two years following the merger.

Full vesting of the retention awards will only occur if savings of at least $300 million are realised.

Executives aside from Davis will be able to receive half the amount if $150 million of savings are realised by the one-year anniversary of the merger.

Davis will be eligible to receive one-third of his award with the final two instalments to be paid on each anniversary until the third.

Xstrata chairman Sir John Bond said retaining Xstrata’s executives was essential for the success of the new entity.

“Xstrata management will be responsible for over 80 per cent – based on the 2011 financial results of Xstrata and Glencore – of the combined group’s earnings, 150 mining and metallurgical assets and 20 major growth projects,” he said.

“We would not have recommended the merger on its current terms without arrangements to secure Xstrata’s management team in the critical initial years of the combined group’s life.”

However, the changes will delay the votes to approve the mergers, due to take place on July 12.

Xstrata will be required to send a supplementary notice to shareholders, delaying the vote.

Bond said he now expected the deal to be completed in early October.

The merger is still likely to encounter more hurdles after major Xstrata shareholder Qatar Holdings yesterday called for a better merger ratio.

Qatar said while it saw merit in a combined entity, it had informed Glencore that 3.25 shares for every one Xstrata share was a more favourable ratio.

Glencore is currently offering 2.8 shares for every one Xstrata share held.

Xstrata did not acknowledge the comments in its statement overnight.