A lorry with job advertisements on its side leaves a Tesco distribution centre in Dagenham, east London on Aug.12, 2013. Reuters/Andrew Winning

(Reuters) - Troubled grocer Tesco has warned on full year profit again, slashing its full-year outlook by almost a third in the latest downgrade sparked by an accounting scandal and intense competition in its home market.

The firm, the world's no.3 retailer, said on Tuesday that on the basis of the changes and investments it has made to date it now anticipates group trading profit for the financial year ending February 2015 will not exceed 1.4 billion pounds.

According to its website analysts were previously forecasting a consensus group trading profit of 1.94 billion pounds for the 2014-15 year.

The firm said that in recent weeks is has implemented new policies and procedures which will govern its commercial income activities and has taken actions to invest in and improve its customer offer.

Customers seeking to save money in a sluggish economy have turned away from the market leader to discounters such as Aldi and Lidl, igniting a price war in British grocery shopping and contributing to a series of Tesco profit warnings.

It said that when it reported interim results on Oct. 23 it highlighted that full year profitability would be impacted by actions it may choose to take and that the commercial income overstatement would affect second half results as it revisited its plans with the new management team, led by Chief Executive Dave Lewis.

Tesco said its new commercial approach would underpin stronger long-term relationships with its suppliers to ensure that revenue recognition is transparent and appropriate.

It added that is has invested further in service, with more than 6,000 more staff in stores, increased product availability on key lines and invested in price.

"The early feedback from customers is encouraging," it said.

Tesco said it will share more detail about the measures it plans to take to improve the competitiveness of the UK customer offer and to strengthen its balance sheet on Jan. 8.