The campaign team for Conservative London Assembly candidate Steve O'Connell has been accused of taking Liberal Democrat literature from a resident's postbox and replacing it with their own propaganda.

Craig Ling, campaign manager for Liberal Democrat candidate Councillor Abigail Lock, claimed yesterday two residents at the Bedzed development in Hackbridge challenged Mr O'Connell while he was leafleting in the area after they caught one of his campaigners taking a Liberal Democrat leaflet out of their letter box and replacing it with their own.

"They were quite outraged actually and, from our perspective, there could be a group of people who are denied our messages," said Mr Ling.

Coun Lock said it was important that voters read all literature so they could make an informed choice. She said: "Also, those leaflets were paid for by residents of Sutton who support us. And they were delivered by volunteers."

They both called for Mr O'Connell, the Greater London Assembly Conservative candidate for Croydon and Sutton, to guarantee his campaign would not do this.

"We want a commitment from Mr O'Connell that this isn't going to be done by him or his campaigners," Mr Ling said.

Mr O'Connell, Croydon Council's cabinet member for public protection, denied he had ever taken Liberal Democrat literature out of a letter box.

"It is something I personally have never done. However, there are a lot of people doing stuff for me.

"This is very clearly not referring to me, although we have been up there delivering. I am not aware of any confrontation or any row."

He said, however, that he would expect his people to pick up other parties' literature for him to see.

"If there's a leaflet on the ground I expect my people to pick it up. If a bit of leaflet is hanging out then they pick it up. I'm sure it goes for Lib Dems, Labour and people generally. I don't think there's a big story," he said.

A spokeswoman for the Conservative Party said she could not comment on the allegations but that such behaviour would not be acceptable.

"We don't have any standard canvassing rules that we issue but we certainly wouldn't encourage anybody to do anything against the law."