Planned Parenthood has announced that it is opening a new 18,000-square foot 'mega-clinic' in southern Illinois after more than a year of secret construction.

The new facility, in Fairview Heights, will begin accepting patients earlier this month and can serve as many as 11,000.

The clinic is only 13 miles from St Louis, where Missouri's last abortion clinic remains and is fighting to stay open.

It's also close to the borders of states such as Arkansas and Kentucky, where abortion laws are much stricter than they are in Illinois.

According to CBS News, Planned Parenthood used a shell company to build the clinic under the code name 'Alaska'.

Planned Parenthood is set to open an 18,000-square foot 'mega-clinic' in Fairview Heights, Illinois (pictured), that was built in secret

Dr Colleen McNicholas, chief medical officer of Planned Parenthood of the St Louis Region and Southwest Missouri, told CBS News that the clinic was built in secret to avoid protests or construction delays.

'We were really intentional and thoughtful about making sure that we were able to complete this project as expeditiously as possible because we saw the writing on the wall,' Dr McNicholas said.

'Patients need better access, so we wanted to get it open as quickly as we could.'

She told CBS News that other Planned Parenthood construction projects have been stonewalled after the public learned that abortions would be provided at the sites.

Dr McNicholas said that, for one clinic, a communications company refused to install telephone lines and internet service.

For another clinic, a cabinet maker took an order, but then refused to deliver it.

The new Illinois facility is set to begin accepting patients later this month and Dr McNicholas says she expects several an influx of them from Missouri, reported CBS News.

It comes after a law passed in Missouri in May that bans abortions after eight weeks.

The law is one of the most restrictive in the nation and activists contend it effectively forbids most abortions since many women do not know they are pregnant yet at eight weeks.

Abortions are allowed after the eighth week only in the case of medical emergencies, and there are no exceptions for victims or rape or incest.

Any provider who performs abortions after eight weeks could be sentenced up to 15 years in prison.

Several other US states with Republican-controlled legislatures have passed similar laws in what is seen as not just a political, but also a moral, fight.

Five states - Georgia, Kentucky, Louisiana, Mississippi and Ohio - have all passed restrictive abortion laws after six weeks' gestation.

Alabama has passed what is perhaps the most extreme restriction, banning abortion from the time a woman 'knows she is pregnant'.

There are no exceptions for rape and incest and doctors who perform abortions can be charged with a felony and be sentenced up to 99 years in prison.

However, all these bills have been blocked by federal judges and none of them are in effect.

By comparison, Illinois has expanded access to abortion. In June, Governor JB Pritzker signed the Reproductive Health Act into law, which establishes the fundamental right of a woman to have an abortion.