Welsh nationalists have accused Tesco of being too cosy with the government.

There were question marks over the "ethics of the relationship" between the chain and Labour, said Plaid Cymru shadow enterprise minister Alun Ffred Jones ahead of the Welsh Assembly elections this week.

Tesco boss Sir Terry Leahy's knighthood and appointment as Gordon Brown's special adviser on business were evidence of its close links, he said, adding that Tesco's "ever-expanding property and land portfolio" coupled with Labour's responsibility for planning guidelines made this close relationship questionable. He also claimed that Tesco had made cash donations of £54,000 to Labour since 2003.

A Tesco spokesman said the money paid to Labour was for sponsorship of receptions at its annual ­conferences.