BP Chief Executive Bob Dudley promised long-term growth after a weak performance for the next few months, in an attempt to ease investors' frustration at the oil major's sluggish share price.

BP reported second-quarter replacement cost net income of $5.31 billion on Tuesday, compared with a loss of $16.97 billion in the same period last year that included the cost of tackling its massive Gulf of Mexico oil spill.

The underlying results fell short of analysts' forecasts and benefited less than rivals are expected to from a 50 percent rise in crude prices from a year ago.

The company said maintenance work in the North Sea and Angola and continued outages in the Gulf of Mexico had weighed on results in the quarter and would continue to impact performance in the second half of the year.

Dudley said deals to secure new reserves this year would help drive performance in 2012 and 2013.

BP investors are frustrated at the share price which has failed to recover materially in the past nine months despite some progress in oil spill lawsuits and indications the final bill will be less than many earlier feared. BP shares were down 2.3 percent at 0724 GMT.

Some investors feel the CEO lacks a clear strategy for recovery.

Dudley addressed the frustration, telling shareholders: We are committed to seeing the true value of the business more strongly reflected in our share price.

BP said oil and gas production fell 11 percent in the quarter to 3.43 million barrels of oil equivalent per day, after the company sold fields to pay for the spill.

The company again increased its estimate for the cost of dealing with the spill, adding around $500 million to the bill, although contributions of $1.1. billion from partners allowed the total charge taken by BP to be reduced.

Excluding one-offs, the replacement cost result was $5.61 billion, below an average forecast of $6.02 billion, from a Reuters poll of 12 analysts.

(Editing by Erica Billingham)

Angola