Oil and gas explorer Bowleven has received overwhelming shareholder backing for the £150 million deal which will see it sell off two-thirds of its principal asset for the cash it needs to continue exploration in Africa.

But at a meeting held in Edinburgh to approve the deal yesterday, the AIM-listed minnow with a chequered history also received a stinging reminder of investor frustration with its lack of progress since being founded 15 years ago to find oil offshore Cameroon.

Former company adviser Tim Noble called on the board to deliver some of the proceeds back to disgruntled shareholders while founding director Mark Lironi questioned whether spending all the cash on further exploration was "a matter of job preservation".

Chairman Ronnie Hanna said there was a 99.5 per cent investor vote in favour of the $250 million deal that will see Russian oil giant Lukoil take 37.5 per cent and African group New Age take its stake from 25 to 37.5 per cent in the Etinde permit.

"The board is recommending this transaction as it accelerates appraisal of the acreage which we believe will generate increased value for shareholders more quickly," Mr Hanna said.

"In essence we believe the larger cake will be of benefit to our smaller stake.

"Very importantly it will provide cash for us to develop our other activities, and help particular areas of exploration where I think our skills are already proven."

He said approval for the Etinde project was now with the president's office.

The deal with Lukoil and New Age had been given a conclusion deadline of August 31, "in the hope that the authorities would respond with a bit more urgency", Mr Hanna said - though it could be extended by mutual agreement.

Shareholder Mr Noble, former head of Noble and Co which was Bowleven's nominated adviser until 2006, then spoke up.

He said: "As shareholders we have all been long-suffering....we thought we were backing Bowleven to produce oil and gas out of the Etinde permit, now it has completely changed and effectively we will be backing Bowleven into completely different areas elsewhere.

"I would have thought there should be some payment to shareholders to reflect the fact that we have got cash out of the Etinde permit, maybe there should be some money back into their hands." Mr Hanna said: "We still have big interests in Cameroon which we think will require further investment."

The company also had acreage in Kenya which would become cash-hungry at a later stage.

Mr Lironi, former director and a substantial shareholder, said since Bowleven came onto the AIM a decade ago it had spent $500 million on an area known to have oil and gas reserves and admittedly "hasn't had a dry well". But in that time the company's market value rose from £110 million to £120 million.

He added: "The shareholders are extremely disappointed there has been nothing to show in ten years, resources have increased, potential has increased, but there is no value coming back to the shareholders."

He supported Mr Noble's call for a dividend, said huge amounts of capital might not actually be needed, and warned some investors saw it as job preservation - "that is a hard one but that is how they see it".

Mr Hanna said: "It is important that the company has a look again at the strategy."

The chairman said afterwards that institutional investors were all supportive and had not raised the issue of a dividend. He said Waseem Shakoor, a public critic of the deal said to be a major shareholder, was not on the share register.

Mr Lironi said afterwards he did not want to see the company blowing huge amounts in new exploration territory before it had any cash flow, adding: "I am disappointed but optimistic."

The shares, which hit 398p in January 2011, were unchanged at 40.25p.