By Anna Horsbrugh-Porter BBC reporter in Colombo

Sri Lanka's prime minister has returned from the United States after an official visit being seen at home as widely successful.

Ranil Wickremesinghe is the first serving prime minister to have been received at the White House for 18 years.

It was crucial for him that the trip went well. After eight months of government, his honeymoon period seemed to be over.

The Sri Lankan prime minister is under increasing domestic pressure over the rising cost of living, and the apparent stalling of the peace process.

Fruitful trip

But he has come back triumphant from America, saying he has obtained "a security net of international co-operation" to provide a back-up to the ceasefire.

President George Bush declared his support for Mr Wickremesinghe after their meeting, calling him courageous and saying he trusted his leadership and judgement.

While talking to a group of journalists in Washington, Ranil Wickremesinghe described the current peace situation.

He said: "We are walking on a tightrope with grease on it, and without a safety net probably with broken glass at the bottom."

But the five-month formal ceasefire was given a boost on Sunday when a Sri Lankan cabinet minister met the Tamil Tiger's chief negotiator in London on his way home from the United States.

Trade accord

It is the first time such high-level talks have taken place, and it is hoped this will break the current deadlock over when direct talks between the government and Tamil Tigers will actually start.

Sri Lankans hope the future holds peace

The talks were originally scheduled for June, but have been shifted forward each month.

Apart from bringing back new hopes and backing for long-term peace in his country, Mr Wickremesinghe also said he had obtained US support in the fields of intelligence, development, defence and trade.

While he was in Washington, a document between the two countries was signed laying the foundations for a future free-trade agreement.

The Trade and Investment Framework Agreement, or TIFA, is designed to boost international trade, investments and economic co-operation between Sri Lanka and the United States.

US official to visit

In all the prime minister has returned to widespread praise for his official trip, not least for the fact that US Deputy Secretary of State Richard Armitage is expected to visit next month on the strength of the Washington meetings.

He will be the most senior US Government official to come to Sri Lanka during the recent past.

But at home Mr Wickremesinghe has come back to find his parliament in disarray, and last week fighting broke out in parliament during his absence.

The row was over allegations that the president had carried either a bomb or a video camera into a cabinet meeting.

Even with US support, the prime minister has a daunting task ahead of him in securing a lasting peace and economic regeneration for his country.

He also has to work on preserving the already fragile relationship with President Chandrika Kumaratunga.