I am a resident Alien here in the US and file taxes with the IRS. I own property in the UK which I intend to sell, what are the tax implications of selling this property?
There is no income or expenses from the property which I effectively use as a residence when returning home to visit family. I have owned the property for >10years.

You would report the sale as a capital gain. If you make a profit on the sale (meaning sell it for more than your cost basis) you would pay capital gains tax on the amount of profit.

1. Since the property is in UK, you may be paying income tax in UK on the capital gains from the sale of property.
2. For the US taxes, you have to figure out if you are eligible for exclusion of $250,00 from the sale of the main house. For this, did you live in the house for more than 2 years in last 5 years? Read IRS publication 523.
3. If you are not eligible to exclude the gain, then you will report the income (long term capital gain) on schedule D (Form 1040). You will also claim credit for the taxes paid in UK.

Note that if you pay taxes on the sale to the U.K. you can file Form 1116 to claim a Foreign Tax Credit for the passive income from the sale of the property. This assumes you sell the property for a gain. If the property is sold at a loss, no taxes should be due for either the U.K. or the U.S. though the sale WILL have to be reported on Schedule D.

Loss from sale of home property is not deductible in U.S.