Traffic on Europe's main north-south road axis, via the Gotthard tunnel in Switzerland, returned to normal on Saturday after two days of tailbacks and delays.

At one stage on Friday, more than 850 trucks were blocked on the road heading towards the Chiasso frontier post on the border with Italy.

Facilities at Chiasso have been stretched to the limit by large numbers of trucks - up to 5,500 a day - since a new heavy goods vehicle tax was introduced in January. Transit traffic has increased by 15 per cent with the arrival of 36 and 40 tonne lorries.

Tensions rose overnight as many truck drivers were forced to sleep in their vehicles. Some attempted to block the route to cars in protest at the delays.

"To ensure this situation does not repeat itself, " said Flavio Ghezzi, a traffic police officer in Ticino, "we would have to find parking space for a thousand heavy goods vehicles, which is totally impractical."

Hans Werder, general secretary at the department of transport, says presence on the roads has to be eased. "We have a massive growth of traffic on the road," Werder told swissinfo, "and it shows that we should try everything to transfer the goods from road to rail."

The authorities in canton Ticino acted on Thursday evening to counter the backlog that had built up at the Italian border by closing the north-south part of the motorway.

The officials also had to face another headache, the breakdown of one of the electronic tax machines at which drivers have to pay their tax.

The A2 freeway was shut down between Giornico and Lavorgo on its north-south axis to let trucks park there while waiting to go through customs.

Lorries have also been held up by the police on the other side of the Gothard. Twelve truck drivers protested against the delays on Friday, blocking the freeway between Faido and Biasca.

The Swiss road hauliers' association said the situation was "unacceptable and inhuman" and called for an increase of capacity at the Chiasso border post.

Alf Arnold, of the environmental pressure group, Alpine Initiative, said Switzerland has become too attractive for heavy goods vehicles.

"The HGV fee is not high enough," Arnold told swissinfo, "and we should not be trying to make it easier for lorries to go through Switzerland, because of the environmental impact."

The Ticino authorities say the measures are only temporary and exceptional. They have called on the federal government to act and assume its share of responsibility, suggesting the creation of parking zones for up to 1,000 vehicles elsewhere in the country.

The Swiss government has stressed the problem of congestion in and around the Gotthard tunnel is not just a domestic issue.

"Switzerland cannot solve this problem alone," Werder told swissinfo. "We must cooperate with Italy, Germany, Holland and other countries."

swissinfo with agencies