By Frances Harrison
BBC correspondent in Colombo
A group of Sri Lankan opposition parties have warned that the current peace process is paving the way for the country's division.
President Kumaratunga (R) has been critical of the peace process
The group is dominated by President Chandrika Kumaratunga's Sri Lanka Freedom Party (SLFP) and the revolutionary leftist People's Liberation Front or JVP.
They say they have almost formed a coalition opposed to Prime Minister Ranil Wickramasinghe's policies.
The alliance accuses the prime minister of being a virtual puppet in the hands of the Tamil Tiger rebels.
Opposition activists say they are planning a mass anti-government protest on Monday in the capital.
The SLFP says it has gone 90% of the way towards forming a pact with the JVP.
The peace talks are said to be dividing the island
The final 10% of the work on forging a common stand will, they say, be completed by the end of the month.
In the meantime, they have come together in an alliance to protect the country from the Tamil Tiger rebels whom they describe as "fascist" and "terrorists".
The SLFP says the year-old ceasefire agreement with the rebels is completely flawed.
The SLFP says that if it came to power, it would negotiate with the Tigers, but with "strong benchmarks and no appeasement".
But sharing the alliance is the JVP, whose propaganda secretary has repeatedly refused to spell out the party's current stance on negotiations with the Tamil Tigers.
Previously, the party had opposed talks for a one-year period until the country's economic problems had begun to be dealt with.
The opposition says it plans to bring 500,000 people onto the streets to protest against the government next week.
Already it alleges a minister of the ruling United National Party is working to discredit them by organising his goons to attack Tamil shops and then put the blame on opposition demonstrators.