Ahead of the fourth phase of assembly polls in Uttar Pradesh, Congress President Sonia Gandhi has accused Prime Minister Narendra Modi of depriving people of their welfare schemes.

Saying she had abstained from election campaign "due to some reasons", Gandhi said in an open letter that Rae Bareli and Amethi were "an integral part of our lives".

"Our is a special relationship, the biggest asset of my life," she said in the letter addressed to voters in the two constituencies.

Hitting out at the Modi government, Gandhi said: "The central government is depriving you of welfare programmes deliberately and I am deeply pained to see this happening."

She urged the electorate to vote for Congress candidates. "This would further strengthen me and the development of the constituency would happen at a greater pace."

In her letter, Gandhi made no reference to the Congress alliance with Uttar Pradesh's ruling Samajwadi Party.

Fifty-three constituencies will see polling on Thursday in the fourth phase of staggered assembly elections in the state including five seats in Rae Bareli and two in Amethi.

This is the first time Gandhi has skipped election campaign for the party she has headed since 1998.