An elevated train line linking Bangkok's city centre and its main airport will be fully open for service next week after months of delays, the Thai state railway said Wednesday.

The non-stop "airport link", which covers 28 kilometres (17 miles) and cost 25.9 billion baht (800 million dollars), will officially open on Monday. Trains are due to run daily every 40 minutes, between 6am and midnight.

After months of test runs, the express service will offer passengers a 15-minute journey to Suvarnabhumi airport from Bangkok's centre for 100 baht, a spokeswoman for the State Railway of Thailand said.

Passengers returning the same day will not need to purchase another ticket.

A second city line will offer a 30-minute journey at a cheaper rate, stopping at eight stations along the way.