Holidaymakers to Ecuador and the Galapagos Islands face disruption after the Reventador volcano erupted last Sunday, depositing two million tonnes of ash onto Ecuador's capital city, Quito. Quito airport was closed all week - visitors have been flying in and out of Guayaquil, 280km southwest - and another explosion on Thursday has cast doubts over its anticipated reopening tomorrow.

Latin American Travel Association chairman Edward Paine has recommended that people check with their tour operator whether their holiday is going to be affected. The Foreign Office has advised against non-essential travel to Quito and the surrounding highlands.

The first KLM flight due to arrive at Quito after the blast was rerouted to Bonaire in the Dutch Antilles; since then Iberia, KLM and Continental Airlines have been rerouting flights to Guayaquil, the country's second city, and bussing their passengers back to Quito - if they still wish to go there.

Flights from Guayaquil to Galapagos were also grounded on Monday as the ash cloud - 4km (2 miles) high - headed towards the flight path, but were reactivated on Tuesday.

Due to the ash in the air, tour operators Kuoni, South American Experience and Travelbag Adventures re-accommodated their clients in Guayaquil. Travelbag Adventures spokesperson Brian Wood said: 'It's a shame, as these travellers will miss out on one of the great colonial cities of the old Spanish empire.'

Trips will start back into Quito as soon as the airport reopens, but South American Experience director Andre Demendonca warned: 'Trips into the jungle region of Oriente, close to the volcano, have stopped for the time being. If our passengers elect not to travel because this part of their trip is affected, we will give them refunds.'

The eruption of Reventador at 2am last Sunday, continuing until Monday evening, caused ash to hover over Quito (population 1.5 million) for days. One man died from respiratory problems before the cloud was dissipated by heavy rainfall on Wednesday. There was another smaller explosion on Thursday.

While the volcano is still active, the Ecuador Geophysical Institute said any subsequent explosions should be relatively small and would not affect Quito. If no further volcanic activity occurs, forecasts are that the airport, whose runways were covered in ash, will be cleared for action on Monday. Other problems caused by the debris - a clogged sewage system, powercuts and some contamination of the water supply - may take longer to resolve.

The government of Ecuador declared a local emergency and is making preparations for the potential evacuation of 3,000 people from highland areas closest to the volcano. Quito is 95km west of Reventador, on the other side of the Andes mountain chain, so there is no risk of lava damage in the capital.

Last week's eruption was no surprise, said Professor Bill Maguire, director of the Benfield Greig Hazard Research Centre, London. 'The volcano has erupted four times a century since 1541. I don't think we'll hear any more from Reventador for a while.'

Travel updates can be found on www.southamericanexperience.co.uk. Foreign Office travel advice can be found on www.fco.gov.uk.

· South American Experience (020 7976 5511); Travelbag Adventures (01420 541 007); Kuoni (01306 747 002).