By Marc Jones and Helen Reid

LONDON (Reuters) - Colombia is likely to start "discussions" in November about cutting its 7.75 percent interest rate, Finance Minister Mauricio Cardenas said on Wednesday.

Cardenas also said he was hoping to include the issue of reducing taxes on foreign investors' bond portfolios into a wider tax reform bill which is set to be finalised by the end of the year.

Cardenas, who sits on the central bank board, had earlier told the Colombia Business Forum event in London that easing inflation would allow interest rates to fall. Speaking to reporters on the sidelines of the conference, he said:

"It is likely the discussion (on cutting rates) will begin in November."

"I'm very optimistic that based on some preliminary information we have on food prices, that inflation is going to be below 7 percent for the month of October and by the end of the year it will be close to 6.1 percent," he added, saying that it should then continue to head toward the central bank's preferred level of 2-4 percent.

Cardenas also said he hoped for talks with Congress over a key tax reform and to include the issue of taxing bond portfolios in the wider bill.

Many fear that a tax reform seen as critical to resolving the country's budget woes will run into trouble in Congress because of the tough political environment. The reform envisages raising value-added tax but many fear it will choke growth which is already at a six-year low.

"We are hoping to engage in a conversation (about taxation of bonds from foreign investors) during the deliberation (with Congress politicians)."

"That would have to happen in the context of the tax bill which should be enacted before the end of the year. It would be part of the tax bill," Cardenas said.

Many of Colombia's problems stem from the fall in global oil prices. More recently, the electorate voted against a hard-won peace deal with FARC Marxist rebels.

Cardenas predicted that Brent crude futures would stay around $50 per barrel next year before rising to around $60 toward the end of the decade.

"We think oil prices are going to go up, but not making an assumption that this will happen anytime soon," he added.

(Additional writing by Sujata Rao in London; Editing by Andrew Heavens)