Tesco has come under pressure from US presidential candidate Barack Obama to meet with the UFCW grocery workers union in regards to employment at its US Fresh & Easy chain.

Obama has sent a letter to Tesco CEO Sir Terry Leahy urging the supermarket chain to discuss "the principles of partnership" with the union. He also called on the company to "reconsider your policy of non-engagement in the US". Tesco has so far avoided dialogue with the UFCW.

It is the second letter to Tesco that Obama has sent, following a previous communication to the Fresh & Easy chief executive Tim Mason in November.

In particular, the UFCW wants Tesco to offer its Fresh & Easy workers the same employment rights as staff who are union members in the UK.

Tesco said yesterday: "We strongly believe that union membership is a matter of individual choice and if our people want to join a union then they can and will. All the signs so far are that there is little interest in doing so."

UFCW officials are expected attend Tesco's annual shareholder meeting in Birmingham tomorrow (28 June).