SOAP-ERROR: Parsing WSDL: Couldn’t load from … : failed to load external entity …

I had written some code using Magento API, it worked fine on my local machine but when I transferred the same code to my linux server I got the following error:

[shell]
SOAP-ERROR: Parsing WSDL: Couldn’t load from ‘http://mydomain.com/api/soap/?wsdl=1’ : failed to load external entity “http://mydomain.com/api/soap/?wsdl=1”
[/shell]

When I opened the URL ‘http://mydomain.com/api/soap/?wsdl=1’ directlty in my browser, it displayed the wsdl file as expected.