NEW DELHI - Police in the Indian capital put up barricades, stepped up security and warned of traffic congestion on Thursday as thousands of protesting farmers were due to arrive for a rally in support of their demand for higher crop prices.

Thousands of farmers began a 'Delhi Chalo' (Let's go to Delhi) march last month to demand higher guaranteed prices for their crops but were stopped by police armed with tear gas and water cannons about 200 km (125 miles) north of the capital, where they have remained camped since.

The protesters, most of who belong to the northern state of Punjab, have urged farmers across the country to gather at Delhi's iconic Ramlila Maidan (ground) on Thursday to escalate their campaign, days before general elections are called.

Police have permitted 5,000 farmers to gather at the ground but farmers' leaders said they could not promise to stick to that limit, local media reported.

"A huge gathering of people from all parts of India is expected to attend the protest," Delhi Police said in a traffic advisory on Wednesday.

Police in the neighbouring suburb of Noida also warned commuters that there may be traffic congestion and diversions on routes leading into Delhi as vehicles entering the capital would be "checked".

Farmers' leaders said last week that people from several central and northern states were expected to participate in Thursday's rally, while farmer groups from southern and western India also said they were preparing to join the protests.

The protest comes weeks before national elections, due by May, in which Prime Minister Narendra Modi is seeking a rare third term.

Farmers say at least one protester has died in clashes with police and dozens more have been injured.

A similar year-long protest two years ago had forced Modi to repeal some farm reform laws in his biggest political defeat.

(Reporting by Sakshi Dayal; Editing by YP Rajesh and Raju Gopalakrishnan)